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Modern Slavery and human trafficking: offences and defences, including the section 45 defence

Updated: 30 April 2020; Updated: 2 December 2021; Updated 6 July 2022; 22 December 2023; 26 January 2024|Legal Guidance, International and organised crime


This prosecution guidance addresses two key themes and comprises two parts:

  • the prosecution of modern slavery offences and the suspects and defendants alleged to have committed them, and;
  • the non-punishment of identified victims, including the statutory section 45 defence, duress and the practical application of prosecutorial discretion, to ensure the UK’s commitment to the internationally agreed obligations to identify and safeguard victims of modern slavery.

Part 1 – modern slavery offences

The Modern Slavery Act 2015 (“the 2015 Act”) consolidated previous legislation criminalising offences of slavery and trafficking for all forms of exploitation. It came into force on 31 July 2015 and does not apply to offences committed before then.

The offences arising under the 2015 Act are:

In this guidance, references to a defendant or suspect alleged to have been involved in “modern slavery”, or a victim of “modern slavery” is reference to all of the conduct caught by sections 1, 2 and 4 including human trafficking.

These offences are all triable either way. The offences contrary to sections 1 and 2 carry a maximum sentence of life imprisonment on indictment. The offence contrary to section 4 carries a maximum sentence of 10 years’ imprisonment on indictment, save where it is committed by kidnapping or false imprisonment, in which case a maximum sentence of life imprisonment applies.

The Director’s Guidance on Charging (Sixth Edition) strongly recommends that investigators seek early advice where modern slavery charges are being considered. One reason for this is that victims and witnesses in modern slavery cases may be vulnerable and/or intimidated. Prosecutors should work closely with the police to consider the support and protection which can be given to these victims and witnesses. Consideration should be given to the range of special measures available for victims and witnesses to give evidence at court and appropriate applications should be made for the same. Early consideration should be given to whether a case can be prosecuted where victims and witnesses are unable or unwilling to give evidence.

Another early issue which prosecutors may raise with investigators (although the decision and the conduct of any application remains with the investigator) is whether a Slavery and Trafficking Prevention Order ought to be sought at this stage, or post-conviction, or at all: see sections 14 and 15 of the 2015 Act.

Information about the detailed training material available can be obtained from each Area's modern slavery lead.

Case strategy

From the early advice stage to the charging decision, a number of the considerations should be addressed as part of the case strategy, including:

  • If considering section 1 charges, how is the case to be put on the evidence available – slavery, servitude, forced or compulsory labour? What other reasonable lines of inquiry should be followed to establish the seriousness of the conduct?
  • If considering section 2 charges, how is the case to be put on the evidence available on the form or forms of exploitation within section 3? What other reasonable lines of inquiry should be followed to establish the exploitative purpose of the travel in section 2 offending?
  • What support is going to be given to the victims to give evidence?
  • What are the evidential opportunities to prosecute the case if the victims do not support the prosecution from the outset or later withdraw support or are unavailable to give evidence?
  • What reasonable lines of inquiry should be followed in respect of material overseas?

Section 1 – Slavery, Servitude and Forced or Compulsory Labour

Slavery, servitude and forced or compulsory labour are not defined in the 2015 Act. In SK [2011] EWCA Crim 1691 (a pre-2015 Act authority but confirmed subsequently to remain good law) the Court of Appeal considered and found assistance from various authorities which may be distilled as follows:

  • each of these is a serious offence in its own right
  • slavery is the most serious, followed by servitude and then forced or compulsory labour
  • slavery is exercising the right of ownership of another person as one might an animal or an object
  • servitude is the imposition, by coercion, of an obligation to provide services
  • forced labour is direct compulsion to work for another
  • compulsory labour is indirect compulsion to work another
  • in both cases compulsion means the work is not offered voluntarily and is exacted under the menace of a penalty
  • in both cases this need not be manual work and covers any work or service

In R v Rooney (Martin Senior) [2019] EWCA Crim 681, the Court of Appeal noted that the menace “can also take subtler forms of a psychological nature, such as threats to denounce to the authorities a worker whose employment status is illegal. The assessment of whether a service required to be performed falls within the definition of [forced or compulsory labour] must take into account all the circumstances of the case in the light of the underlying objectives of Article 4.” The Court stated that there will be circumstances of exploitation of workers which do not amount to this offence: for example, where an employer merely pays very low wages or flouts health and safety requirements. Prosecutors should consider the industry standard terms and conditions as a relevant factor here. They should also consider non-physical compulsion such as psychological means of exerting control including humiliation, threats and insults or isolating a victim.

Chapter 3 of the Home Office statutory guidance sets out a comprehensive list of signs that can indicate that a section 1 may have been committed.

The kind of behaviour that would normally, of itself, be evidence of coercion and includes (but is not limited to):

  • violence or threats of violence against the victim or the victim’s family by the employer or the employer’s representative
  • threats to expose the worker to the authorities, for example because of the worker’s immigration status or offences they may have committed in the past
  • the person’s documents, such as a passports or other identification, being withheld by the employer
  • restriction of movement
  • debt bondage (including, making accommodation a condition, charging a high rent compared to earnings)
  • withholding of wages

Other factors that may be indicators of forced labour include (but are not limited to):

  • the worker being given no information, or false information, about the law and their employment rights;
  • excessive working hours being imposed by the employer;
  • hazardous working conditions being imposed by the employer;
  • unwarranted and perhaps unexplained deductions from wages;
  • the employer not paying the full tax or national insurance contributions for the worker;
  • the absence of any formal or implied contract of employment;
  • poor accommodation provided by the employer;
  • misleading information having been given about the nature of the employment;
  • the person being isolated from contact with others;
  • money having been exchanged with other employers/traffickers etc. for the person’s services in an arrangement which has not been agreed with the person concerned or which is not reflected in his remuneration.

Importantly, section 1(5) states: the consent of a person (whether an adult or a child) to any of the acts alleged to constitute holding the person in slavery or servitude, or requiring the person to perform forced or compulsory labour, does not preclude a determination that the person is being held in slavery or servitude, or required to perform forced or compulsory labour.

Evidence that the victims of the offending consented to it, or an absence of evidence from the victims to rebut consent (because they are unwilling or unable to give evidence) does not prevent a court from concluding that the victims were held in slavery or servitude or require to perform forced or compulsory labour.

The points identified above can be proved by evidence from victims but can also be proved from other sources, including documents, mobile phones and other exhibits seized from a search, photographic or videoed evidence including body worn video, 999 calls, bank records, police or other investigators’ records, records held government by government agencies and evidence from other witnesses. If necessary, the hearsay provisions should be carefully applied: first, to determine whether the evidence is in fact hearsay, and second to decide how to adduce or admit the evidence in accordance with Part 11 Chapter 2 of the Criminal Justice Act 2003 and the Criminal Procedure Rules.

Section 2 – Human trafficking

The UN Protocol to Prevent, Suppress and Punish Trafficking in Persons (‘Palermo Protocol’) provided, in Article 3, the first internationally recognised definition of human trafficking which is cited in in domestic case law:

"“Trafficking in persons" shall mean the recruitment, transportation, transfer, harbouring or receipt of persons, by means of the threat or use of force or other forms of coercion, of abduction, of fraud, of deception, of abuse of power or of a position of vulnerability or of the giving or receiving of payments or benefits to achieve the consent of a person having control of another person, for the purpose of exploitation. Exploitation shall include, at a minimum, the exploitation of the prostitution of others or other forms of sexual exploitation, forced labour or services, slavery or practices similar to slavery, servitude or removal of organs.”

Human trafficking is an offence that covers the movement of a person or people from one place to another with the intent to exploit them.

Section 2 sets out the circumstances which amount to trafficking for the purposes of “exploitation”, defined in section 3 of the 2015 Act.

Importantly, section 2(2) states: it is irrelevant whether the victim (whether an adult or a child) consents to the travel. Thus evidence of consent, or an absence of victim evidence to rebut it, is irrelevant to this charge.

The evidence of trafficking may come from the victim themselves but if they are unwilling or unable to give this evidence other sources may provide it, including CCTV, ANPR and similar in addition to the sources set out in the section above.

For offences of trafficking for sexual exploitation which occurred before 31 July 2015, but after 5 April 2013, see: Trafficking people for sexual exploitation – section 59A Sexual Offences Act 2003.

For offences of trafficking for sexual exploitation which occurred before 6 April 2013, see: Trafficking into the UK for sexual exploitation – sections 57, 58 and 59 Sexual Offences Act 2003. For offences of trafficking for all other forms of exploitation (non-sexual exploitation) which occurred before 31 July 2015, see: Trafficking people for labour and other exploitation – section 4 of the Asylum and Immigration (Treatment of Claimants etc.) Act 2004 as amended.

Section 4 – Committing an offence with intent to commit an offence under section 2 of the Act

This section involves proof of the commission of an offence with intent to commit an offence under section 2 – not section 1. It should therefore be used where there is evidence of an intent to commit the section 2 offence but where the act committed, although a criminal offence, is merely preparatory to the section 2 offence. A non-exhaustive list of examples would include theft or taking of a vehicle to traffic victims, committing a fraud or identity document offence to assist in the movement of persons, assaulting a victim or otherwise incapacitating them to make trafficking easier or kidnap or false imprisonment of that person. Prosecutors should consider whether, in addition, there is sufficient evidence to prosecute inchoate offences, such as conspiracy, attempt or encouraging or assisting – or indeed, if the suspect should be charged with aiding and abetting the section 2 offence, pursuant to section 2 and the Accessories and Abettors Act 1861.

Modern Slavery and Drug Offences

Offending through “County Lines” is a national issue involving the exploitation of vulnerable children and adults by organised crime group members to move and sell drugs, especially crack cocaine and heroin, across the country. For further information, see the Gang related offences prosecution guidance and County Lines offending prosecution guidance. Children as young as 6 years of age have been reported as being recruited and groomed with money, gifts or through relationships to carry out day to day drug dealing.

Vulnerable adults and drug users may have been coerced to become runners or have their accommodation used as an operating base by drug dealers, known as cuckooing. Their consent is often obtained by supplying them with “free” drugs for their own use, creating a debt which they then have to “work off”, or by threats of violence.

Victims may be unwilling to give evidence, either because they do not recognise themselves as victims, due to the grooming aspect of the offending, or through fear of reprisals.

The Court of Appeal judgment in R v K, W, A [2018] EWCA Crim 1432 confirms that because the prosecution does not need to prove a lack of consent by an exploited person, it is not dependent on the ability to call the individual said to have been exploited as a witness.

Supporting Victims

Victims and witnesses in these cases may be vulnerable and this can present challenges in managing and supporting them before and during the trial. They are often deliberately targeted for their vulnerabilities; they may be homeless, addicted to alcohol or drugs, friendless, isolated and destitute. In cases where they have been controlled by discipline, threats or violence, they may effectively become institutionalised. Prosecutors should keep this in mind from the outset of the case, considering these factors and sensitivities when creating a case strategy and working with the police. Victims may be unwilling to engage with law authorities from the outset, or initially engage and then withdraw support. Prosecutors should consider how to prove a case if their evidence is not available, exploring evidential opportunities to do so wherever possible.

It is good practice for the victims to be removed to a private reception centre, where their needs can be assessed and referral made to appropriate support agencies. If it is known that English is not the first language of the victims (and/or the suspects) an interpreter should be available at the point of removal. This will facilitate obtaining evidence from the victims and potentially ensure early evidence capture by way of conversations between the parties. If this facility is unavailable, officers should be advised to capture evidence on their body worn cameras for later translation.

In such cases, the police will have worked with social services for the co-ordination of support services to provide on-going accommodation and retain regular contact leading up to trial. The CPS should liaise with the police in advance of the trial to agree costs of accommodation and transport for the duration of the trial.

To prevent allegations of coaching or inducements, support agencies should be advised to keep their contact with victims to only that necessary and to keep full records of their interactions. They are however third parties. If this third party material is relevant the investigator should obtain it with a view to using it in evidence or disclosing it, as appropriate.

Early consideration should be given to the use of professionals to assist with engaging with victims, especially where there are extreme vulnerabilities. Professionals should be instructed based on the needs of the victim or witness, the expert’s specialism and their ability to engage with the victim.

Where victims are prepared to give evidence, they should be supported. Either because of personal vulnerabilities or, depending upon the circumstances of the offending, they may take significant risks to do so (see Special Measures below). In some cases the use of intermediaries and ground rule hearings should be considered.

Achieving Best Evidence (ABE) – Visually recorded interviews

The published edition of Achieving Best Evidence in Criminal Proceedings: Guidance for Vulnerable or Intimidated Witnesses (ABE) provides full guidance on visually recorded interviews for vulnerable or intimidated witnesses, incorporating best practice.

To minimise the number of interviews required, and therefore any potential negative impact on the victim or witness, the interviews should be well-planned in advance. The victim or witness should be enabled to provide a full account, focussed on any potential offences and further reasonable lines of enquiry, to assist a fair investigation. Where charges are authorised, following the guidance should also ensure that the recorded evidence is suitable for presentation in court.

Whilst the ABE guidance is advisory and not a legally enforceable code of conduct, significant departures from this may have to be justified in the courts. In JB (A Child), Re (Sexual Abuse Allegations) [2021] EWCA Civ 46. The Court of Appeal (Civil Division) considered, and expressed serious concerns about, the failure of investigators to follow the ABE guidance.

Although this arose in a family case, the points made by the Court of Appeal have equal application in respect of criminal proceedings. The Court restated comments on complying with ABE guidance in criminal cases: Re Y and F (Children) Sexual Abuse Allegations) [2019] EWCA Civ 206. Ultimately, serious failings in the following of the ABE guidance may lead to arguments around the exclusion of evidence.

Special Measures

Under section 17(4) of the Youth Justice and Criminal Evidence Act 1999 (YJCEA) a victim of a sexual offence or victims of offences under section 1 and 2 of the 2015 Act (victims of forced labour and trafficking for sexual and non-sexual exploitation) are automatically eligible for assistance unless they wish to opt out.

The investigating officer should discuss Special Measures with the victim to assess what would assist them to give their best evidence and the prosecutor should immediately raise Special Measures if it is not adequately dealt with in the information provided by the police For further information see the Special Measures prosecution guidance.

Section 28 Youth Justice and Criminal Evidence Act 1999 (YJCEA)

The use of section 28 for victims of modern slavery has been rolled out to all Crown Court locations.

Under section 28 YJCEA victims can pre-record their cross-examination before trial where their evidence in chief has also been recorded and they meet the criteria of section 17(4) Youth Justice and Criminal Evidence Act. This can also be used alongside other special measures such as giving evidence over a live link, using privacy screens so victims cannot see the defendant while they give evidence and clearing the court of all non-essential personnel. Section 28 may be a particularly useful special measure for victims of modern slavery who want to return to their home country or otherwise seek to rebuild their lives.

These cases should be identified as early as possible by the investigator and prosecutor. There should be early disclosure of unused material and resolution of evidential issues where possible. The case should be flagged at the magistrates’ court stage for the setting of a timetable in the Crown Court including a ‘grounds rules hearing’. There needs to be continuity of trial counsel and judge. The victim should be in the UK for the section 28 hearing.

Victims who wish to return to their home country

Where a victim has chosen to be repatriated to their home country and they do not wish to return to the UK, an application may be made for their evidence to be given through television link from their country. A formal application by way of International Letter of Request may be required and an application should be made as soon as the witness has indicated that they would like a live link. It can take 6-8 weeks for a request to be considered. It is advisable to contact the Liaison Prosecutor in post to discuss any country-specific requirement and expedite the request. A fixed date for trial should be requested at the Plea and Trial Preparation Hearing to facilitate the use of a link. For further information on the provision of live links see Live links prosecution guidance.

Reporting Restrictions

Prosecutors should consider court reporting restrictions for victims and witnesses in modern slavery offences as part of the case strategy. The court may impose reporting restrictions so that, during the victim’s lifetime, no details may be published if they are likely to lead members of the public to identify that person as a possible victim of crime. This includes their name, address, identity of any education establishment or place of work, or any picture of them.

Potential reporting restrictions:

  • Automatic lifetime reporting restrictions for a victim under section 1 Sexual Offences (Amendment) Act 1992 – this applies to the victims of any offence listed in section 2 of that Act including human trafficking, rape and other serious sexual offences.
  • Discretionary lifetime reporting restrictions under special measures provisions – vulnerability (section 46 YJCEA). The court may impose the restriction if it considers the witness is vulnerable and the reporting restrictions are likely to improve the quality of evidence given by the witness or the level of their cooperation with proceedings.
  • Discretionary lifetime reporting restrictions under special measures provisions – fear or distress (section 45 YJCEA). The court may impose the restrictions if it considers the preparation of the case is likely to be diminished by reason of fear or distress of the person in connection with being identified by members of the public as a person concerned in the proceedings.

Section 45 of the YJCEA also provides a discretionary power to restrict reporting the identity of victims, witnesses and defendants under the age of 18 who appear in magistrates’ courts and/or the Crown Court.

Media coverage of cases can be beneficial in that it raises public awareness of types of modern slavery and human trafficking offences within their communities. It also demonstrates how seriously this is taken by law enforcement and the wider criminal justice system. However, a media handling strategy should be put in place to ensure the safety of the victims and witnesses both here and abroad. Stringent reporting restrictions are in place within the UK but not necessarily overseas which may cause difficulties victims and their families.

Witness Protection and Anonymity

If the prosecutor is informed by the police or other source (for example, witness care unit) that a witness is fearful of giving evidence, the prosecutor should liaise closely with the police to consider the range of options available to them. The CPS guidance on Witness Protection and Anonymity should be considered.

Interpreters and Intermediaries

Arrangements for the selection and engagement of appropriately qualified interpreters can be found in the Revised Agreement on the Arrangements for the Attendance of Interpreters in Investigations and Proceedings within the Criminal Justice System. Where appropriate, issues such as gender, political orientation or affiliation, regional origins and cultural background of the interpreter should be considered when selecting an appropriate individual. Any reasonable requirements expressed by the witness should also be considered.

Victims of trafficking and slavery may have been targeted because of their vulnerabilities, such as being deaf, mute or with learning disabilities. In these cases, prosecutors should consider examination of the witness through an intermediary to help the witness to give their evidence at court. They can also provide communication assistance at the investigation stage. The intermediary is allowed to explain questions or answers so far as is necessary to enable them to be understood by the witness or the questioner but without changing the substance of the evidence, (< a href="">section 29 YJCEA). For further information see the Registered Intermediary section contained in the Special Measures prosecution guidance.

International Inquiries

Prosecutors should consider their strategy regarding the obtaining of material from overseas, either informally on a police-to-police basis or, if they have commenced their own investigation into related offending, through formal mechanisms such as Eurojust or Joint Investigation Teams, at the earliest stage. If the CPS has a Liaison Prosecutor for a specific country, then the prosecutor should contact them as soon as possible to assist.

Where there are issues of nationality bar restrictions on the prosecution of suspects, the appropriateness of alternatives to extradition such as transfer of proceedings should be identified early and guidance considered.

For further information on obtaining evidence from abroad, including mutual legal assistance, see the International guidance and any relevant country specific Information.

The obligations under the Criminal Procedure and Investigations Act 1996 to pursue all reasonable lines of inquiry applies to overseas material. See the guidance in Chapter 35 of the Disclosure Manual on International Disclosure Issues for further details.

The obligation on investigators and prosecutors in respect of material held outside the jurisdiction is to take reasonable steps to obtain relevant material. There can be no absolute obligation to obtain material because the material is not held by persons or bodies subject to the jurisdiction of England and Wales: R v Flook [2009] EWCA Crim 682 at [37].

The Attorney General's Disclosure Guidelines set out the position at paragraphs 46 to 54.

Public interest

Offending contrary to the 2015 Act is, by its nature and understood in terms of culpability and harm, very serious. If the evidential stage of the Code for Crown Prosecutors test for prosecution is met, it is highly likely that a prosecution is required in the public interest.

Selection of charges

Given the seriousness of these charges, even where other offences are available, modern slavery charges are most likely to require prosecution. Applying section 6 of the Code for Crown Prosecutors, it is highly likely that these will reflect the seriousness and extent of the offending. The selection of modern slavery charges also means that the court is enabled to impose appropriate ancillary orders including Slavery and Trafficking Reparation Orders and Slavery and Trafficking Prevention Orders (see below). Additional serious charges should also be considered, particularly where they may attract a consecutive sentence: most obviously, where serious offences against the person, sexual offences or drug offences have been committed (in particular in county lines offending). The case of Nixon [2021] EWCA Crim 575 is illustrative. His sentence could have been expressed as consecutive or concurrent to reflect multiple counts relating to drugs offending and modern slavery. The former however meant the court could reflect the different criminality involved and to impose significant sentences on both, which the sentence the Court of Appeal increased.

Prosecutors considering a section 4 charge should address whether there is sufficient evidence for an inchoate offence or whether the suspect has aided and abetted the full section 2 offence. The prosecutor must approach the selection of charges bearing in mind the different maximum penalty for the section 4 offence (10 years’ imprisonment unless false imprisonment or kidnapping) compared to conspiracy, encouraging or assisting or attempting the section 2 offence, or aiding and abetting it, which is life imprisonment.

Evidence gathered during a modern slavery investigation, such as surveillance or financial enquiries, may reveal other criminality which the police should consider for investigation. This might lead to other ways of disrupting criminality, such as money laundering or other financial crime investigations. It might lead to the investigation of other suspects, for instance those who pay for the sexual services of a trafficked victim.

Where there is insufficient evidence to charge modern slavery offences against child victims, offences contrary to the Sexual Offences Act 2003 and/or Children and Young Persons Act 1933 should be considered.


The Definitive Guideline for modern slavery offences under the 2015 Act is published at Offences contrary to the 2015 Act, although triable either way, are all within the unduly lenient scheme: paragraph 2(l), schedule 1 Criminal Justice Act 1988 (Reviews of Sentencing) Order 2006/1116.

Proceeds of Crime

Confiscation proceedings should be considered against defendants convicted of offences contrary to the 2015 Act, noting that sections 1 and 2 are “lifestyle offences” for the purposes of the Proceeds of Crime Act 2002.

Slavery and Trafficking Reparation Orders (STROs)

Consideration of a STRO should take place at the same time as confiscation proceedings are being considered as the power to make a STRO is linked to a confiscation order having been made. The provisions for making a STRO are contained in Sections 8 to 10 of the 2015 Act.


In the absence of confiscation or STRO, prosecutors must consider applying for compensation on conviction.


If a person is convicted on indictment of an offence under section 2 of the 2015 Act, the court may order the forfeiture of a vehicle, ship or aircraft used or intended to be used in connection with the offence: section 11 of the 2015 Act.


Procedures in relation to deportation are dealt with in Sentencing - Ancillary Orders.

Slavery and Trafficking Prevention Orders (STPOs)

The court may make a STPO following conviction if it is satisfied that there is a risk that the defendant may commit a slavery or human trafficking offence and it is necessary to make the order for the purpose of protecting persons generally, or particular persons, from the physical or psychological harm which would be likely to occur if the defendant committed such an offence. The CPS may make such an application under section 14; there is a separate power to apply other than post-conviction by other authorities in section 15.

Part 2 – modern slavery non-prosecution principles and defences, including section 45

The importance of identifying victims of modern slavery

The identification of victims of modern slavery during the course of an investigation and prosecution involves compliance with international and domestic law, the importance of which is codified in treaties and legislation and underlined by international and domestic court decisions.

The Council of Europe Convention on Action against Trafficking in Human Beings (the “Anti-Trafficking Convention”) came into force in the UK on 1 April 2009. Its implementation introduced a number of provisions including mechanisms for early identification of victims, national referral schemes, the granting of recovery and reflection periods and renewable residence permits to victims.

The CPS and its prosecutors must act compatibly with Article 4 of the European Convention on Human Rights (ECHR) which prohibits slavery and forced labour. Further, Article 26 of the Anti-Trafficking Convention requires the UK (and therefore the CPS) to: “... provide for the possibility of not imposing penalties on victims [of trafficking] for their involvement in unlawful activities, to the extent that they have been compelled to do so” as does Article 3 of the Palermo Protocol.

It had been held that, for cases considered pre-31 July 2015, a special category of abuse of process exists in the criminal courts where it is arguable that the prosecutor’s discretion to prosecute has been exercised unlawfully. However, abuse of process arguments can still be raised in cases where the offending is after 31 July 2015 and where the section 45 defence does not apply.

In AAD, AAH and AAI Lord Justice Fulford VP stated at paragraph 142:

  1. The limb two abuse of process jurisdiction [i.e. where it would be unfair to try the defendant] remains available in principle in all Victims of Trafficking (VOT) cases following the 2015 Act, and whether or not they are Schedule 4 cases.
  2. Such jurisdiction is “special” only in the sense that it falls to be exercised in the context of a particular sensitivity required to be applied to VOT prosecutions, having regard to international obligations and specific CPS guidance. The core requirements of unfairness and oppression and illegality (inherent in almost every limb two case) remain central to applications for a stay in a VOT context.
  3. Mere disagreement with a decision to prosecute, following due regard given by the prosecution to the CPS guidance and to any conclusive grounds decision, gives no basis whatsoever for an application for a stay. Decisions to prosecute are for the CPS. Decisions on disputed facts or evaluations of fact are for the jury.
  4. If (in what will be likely to be a most exceptional case) there has been a failure to have due regard to CPS guidance or if there has been a lack of rational basis for departure by the prosecution from a conclusive grounds decision, then a stay application may be available.

Abuse of process was further considered in R v AFU [2023] EWCA Crim 23 where, despite a plea of guilty, the appellant’s conviction was quashed. The Appellant was a victim of human trafficking who had been kidnapped in Vietnam, trafficked to the UK in debt bondage, tortured and put to work in a cannabis house. The judgment confirms that abuse of process is available even where a defendant has entered an unequivocal guilty plea despite legal advice at the time on the availability of a defence, based on the applicant’s instructions.

In this case, the Court reviewed the principles of the duty not to prosecute victims of modern slavery where (1) they have a credible defence under section 45 of the Modern Slavery Act 2015 or (2) their criminality or culpability has been removed or decreased to a point where prosecution does not remain in the public interest, as per R v AAD [2022] EWCA Crim 106. This judgement confirmed that the usual principle of finality does not apply in guilty plea cases where the defendant is a victim of modern slavery.

The court found that at the time [2016] there were operational failures in the identification of the applicant as a victim and in the application of the relevant CPS guidance in force at the time. No full investigation had taken place, despite clear indicators of trafficking from the outset, which lead to a breach of Article 4, ECHR. The conviction was found to be unsafe.

The Court also noted (at paragraph 141) that “on an application to stay the proceedings, for instance on the basis that the Crown had unjustifiably failed to take into account the CPS Guidance when deciding to prosecute, one option available to the judge prior to making a decision would be to adjourn the application to afford the CPS the opportunity to reconsider/remake its decision in light of its own guidance. This approach may be less appropriate, however, if the contention is that the decision was simply unsustainable or perverse.”

The judgment upheld Brecani (below) confirming that SCA decision makers are not experts but did confirm that the SCA’s decision on conclusive grounds is potentially admissible in appeal matters. The judgment also confirmed the limitations on when expert evidence could be introduced and confirmed that there may be cases when the Court of Appeal (Criminal Division) will consider whether the appellant needs to give evidence on appeal.

An appellant’s conviction may be safe in a case where the criminal act is committed by a victim of modern slavery, where a defendant has been correctly advised about a possible section 45 defence and pleads guilty voluntarily following that advice, applying the established principles which apply in such appeals.

This case serves as a reminder to Prosecutors that even if the conviction is safe on UK appeal grounds, where the State’s Article 4 ECHR duties have not been complied with, and an appellant has not been identified as a possible credible victim of modern slavery when they are a victim, their conviction will be unsafe if the following applies:

  • their trafficking circumstances have not been properly investigated
  • had they been properly investigated the appellant would have been shown to have been a victim, and
  • the CPS would or might well not have maintained the prosecution on evidential or public interest grounds.

The National Referral Mechanism and the Single Competent Authority

The National Referral Mechanism (NRM) is the UK framework for identifying and referring potential victims of modern slavery and ensuring they receive the appropriate support. The Single Competent Authority (SCA), is one of the UK’s competent authorities responsible for decision-making in the NRM and is part of the Home Office. The SCA decides whether the individual is a victim of modern slavery. It does not have investigative powers but can request information and therefore makes decisions on the basis of the material provided. Modern Slavery Statutory Guidance is published by the Home Office under section 49(1) of the 2015 Act. The guidance provides advice on how to identify and support victims, the NRM process and the criteria used to determine whether someone is a victim. UNODC Human Trafficking Indicators may also assist.

The role of the prosecutor in relation to the NRM / SCA

Certain public authorities, including the police, have a statutory duty to refer potential victims and to the NRM. The CPS cannot make referrals: it is not a first responder. Where there is a potential victim of modern slavery, however, the CPS should ask the police to make a referral and ensure at the least that the police have considered the question of referral. This is the case whether the person is a victim, witness, suspect or defendant. The police must be advised to investigate the claim, in addition to any NRM referral, if it has not been already. The prosecutor must satisfy themselves that this investigation is sufficiently thorough. All liaison and correspondence with the SCA should be conducted through the police.

A prosecutor must be alert to Indicators of trafficking. A prosecutor may consider that someone is a potential victim of modern slavery based on their own assessment of the case, or following defence representations, or observations from the court or other authority. The obligation exists whether or not the suspect makes a disclosure to this effect or provides any information or evidence of it. Prosecutors should use the statutory guidance to inform their assessment. The police should always be asked to make a referral, unless the police are in possession of clear and sufficient evidence to prove that the suspect is not a victim of modern slavery.

Consent is required to refer an adult into the NRM, but not a child or young person under 18. Where an adult does not consent, public organisations have a ‘Duty to Notify’ the Home Office that they have encountered a potential victim.

To support the SCA in prioritising cases effectively, the prosecutor should ensure that the police have provided the following information to the SCA, together with the relevant factors of each case:

  • Defendant’s full name
  • Date of birth
  • Nationality if known
  • NRM reference number
  • Court and next hearing date
  • CTL expiry date
  • If the defendant is a youth

The police should be asked to confirm what information has been supplied to the SCA and that the SCA has been informed of the significant dates applicable, such as court hearing dates and the timescales by which a response or decision is required from them. Timescales should be agreed between the prosecutor and the police for the police to notify the prosecutor of the SCA decision. If the information has not been provided by the agreed dates, the prosecutor should ensure this has been escalated by the police with the SCA.

The SCA should be updated immediately, by the police, as the case develops (for example, if someone is later remanded into custody, or if a trial date is set / brought forward). Prosecutors should ensure the police have relevant information to do so and advise the police on the need for close engagement with the SCA and the need to record all contact, should the court require assurance and in the event that a custody time limit extension application is required.

Reasonable Grounds Decision

The first stage of the process will be for the SCA to decide if there are reasonable grounds to believe that the person is a victim (“the RG decision”). The test for an RG decision is whether the decision maker agrees there are RG to believe, based on objective factors but falling short of conclusive proof, that a person is a victim of modern slavery. The credibility of the victim’s account will be assessed, taking into account relevant factors such as trauma that may impact on the information provided. General indicators of a potential victim’s behaviour, circumstances and responses to questions are taken into account in reaching the decision.

Conclusive Grounds Decision

The second stage involves a further inquiry. The test used for the conclusive grounds (CG) decision is whether, ‘on the balance of probabilities’, there are sufficient grounds to decide that the individual is a victim.


The SCA aims to make RG decisions within 5 working days of receiving a referral wherever possible and there is sufficient information for it to do so. Emergency support is available for potential victims who would otherwise be destitute during this time.

A positive RG decision entitles the potential victim to a recovery and reflection period for a minimum of 30 days, and until the CG decision is made (at least 30 days) after the RG decision. The SCA has agreed to prioritise cases wherever possible that are listed for plea or trial, or where CTLs are getting closer to expiry. However, this requires sufficient notice to ensure decisions can be made on time and compliance with the obligations for that process set out in the statutory guidance.

During the process, the risks and needs of victims are assessed at various points. Support for potential and confirmed victims is provided through a mixture of mainstream and/or specialist support services. It can include access to government-funded support through the VCC. Child victims are supported by local authorities under their statutory safeguarding duties. The recovery and reflection period is intended, in part, to aid a victim’s recovery from their immediate physical or psychological trauma before deciding whether to support an investigation / prosecution. However, this does not stop the victim from speaking with law enforcement to provide intelligence or information or make a statement if they wish to assist an investigation.

During the recovery and reflection period, further information and evidence will be collected to enable a CG decision to be made. Those adults with a positive decision receive a further period of move-on support based upon the victim’s needs to safely transition out of NRM support. Those with a negative decision receive support for a further 9 days.

Following a positive CG decision, victims may be eligible for discretionary leave to remain that is granted outside the Immigration Rules in accordance with Home Office policy. This may be granted where a victim is assisting the police with their enquiries and/or seeking compensation from their exploiters in UK courts, and it would be unreasonable for them to pursue the claim from outside of the UK; or it is deemed necessary owing to their personal circumstances.

Case Management and the NRM

In accordance with the principles set out by the Court of Appeal in R v D [2018] EWCA Crim 2995 the status of any potentially trafficked defendant should preferably be determined before any plea is entered. On 22 July 2019 a revised PTPH form (PTPH2) came into effect with a specific section relating to suspects who may be potential victims of MSHT. The form asks the defence to highlight whether it is alleged that a defendant is a victim of modern slavery, however prosecutors and judges must also consider this issue to determine whether the prosecution should continue and/or whether the defendant is alleging a defence under section 45 of 2015 Act (see below). If such a defence is raised, a plea should not formally be entered, the staged dates set by the court should be amended to allow a referral to the NRM, or await the decision if a referral has already been made. The normal operation of custody time limits still applies and an application to extend should be made, as necessary.

Disclosure and the NRM

Material created or obtained by the SCA, such as the first responder referral and any records of their encounters with the individual or information gathered from other parties, may be relevant to the investigation. This is third party material for the purposes of the Disclosure Manual and the Attorney General’s Guidelines on Disclosure 2022 and should be obtained and assessed for disclosure.

The investigator should seek the material through a third party material request form which clearly articulates what is being sought and why. Any material deemed sensitive material should be considered in accordance with the CPIA and the guidance in Chapters 8 and 32 of the Disclosure Manual. The material supplied by the SCA to the police will also contain a generic section 9 statement which sets out the role and function of the SCA, how the NRM operates and the evidential standards applied to both the RG and CG decisions. It should be considered as unused material. If it is required as part of the prosecution case it should, whenever possible, be agreed with the defence.

There is a continuing duty of disclosure throughout the life of any case. A defence statement or other development in a case may raise an issue that creates further reasonable lines of enquiry or extends the parameters of relevance to material a third party may hold. Prosecutors must be satisfied they have all the relevant material from a third party. It may be necessary for the police to provide the SCA with further details around the relevant factors in the case so that a further review of material can take place.

The role of the prosecutor: decision-making

In all cases involving suspects/defendants who might be victims of modern slavery, prosecutors should adopt a four-stage approach, set out below, in order to ensure that their review of a case fully and properly applies relevant considerations set out in the Code for Crown Prosecutors. Before reaching the four-stage approach it may be necessary to establish whether or not the suspect/defendant is a child as quite different evidential and public interest considerations apply.

Children – due inquiry as to age

Modern slavery may involve child victims and it is important to establish their age for the purposes of both modern slavery offences and non-prosecution principles including the section 45 defence.

Section 99(1) of the Children and Young Persons Act 1933 provides that “where a person, whether charged with an offence or not, is brought before any court otherwise than for the purpose of giving evidence, and it appears to the court that he is a child or young person, the court shall make due inquiry as to the age of that person …” This issue should be identified at the first court appearance or Plea and Trial Preparation Hearing.

Time may be required for the court to determine the issue and for proper enquiries to be made. The prosecutor should consider the question of age and only proceed on the basis that the person is not a child if they conclude that a court would more likely than not be satisfied of this fact. This is important, because those with responsibilities for victims may apply the presumption in section 51 of the 2015 Act pending the outcome of the inquiry, and the court may approach the inquiry asking itself if the person appears to have attained the age of 18 (see section 99) – but this does not preclude the defendant from raising this as an issue at trial and the prosecutor must remain focused on the standard and burden of proof throughout. See further the prosecution guidance on Children as Suspects and Defendants.

The Four-Stage Approach to the Prosecution Decision

  1. Is there a reason to believe that the person is a victim of modern slavery?
    • If yes, move to Question 2.
    • If not, you do not need to consider this assessment further.
  2. Is there clear evidence of a credible common law defence of duress?
    • If yes, then the case should not be charged or should be discontinued on evidential grounds.
    • If not, move to Question 3.
  3. Is there clear evidence of a statutory defence under Section 45 of the 2015 Act?
    • If yes, then the case should not be charged or should be discontinued on evidential grounds
    • If not, move to Question 4.
  4. Is it in the public interest to prosecute? This must be considered even where there is no clear evidence of duress, or all the elements of the statutory defence under section 45, or where the offence is excluded under Schedule 4.

Stage 1: Is there Reason to Believe the Person is a Victim of Trafficking/Slavery?

As set out above, prosecutors are required to consider this, independently of whether it is raised by the suspect or not.

When assessing credibility, prosecutors should be aware that victims of modern slavery will frequently make late disclosures about their circumstances and may give an untrue account, often because they are told what to say by those responsible, are in fear or suffering trauma. Prosecutors should additionally consider the Home Office Statutory Guidance on credibility.

The status of the SCA decisions and their correlation with the decision to prosecute was considered in 2 landmark cases:

R v Brecani [2021] EWCA Crim 731 this case re-stated the position that the decision of an SCA decision maker does not bind the hands of the prosecuting authority: it is a different test, to a different standard, for a different purpose. The decision-makers are not experts; consequently their decision is inadmissible opinion evidence in a criminal trial. It follows that no trial admissions should be made regarding the decision of the SCA as this is a triable issue for the jury to decide.

However, the SCA findings must be taken into account. If the decision is taken to prosecute, even though there is a conclusive grounds decision that the suspect is a trafficked victim, clear reasons must be recorded, setting out the rationale for that decision. In this case the decision could be departed from because the SCA had not had sight of all the relevant material.

In the case of VCL and AN v United Kingdom (2021) 73 E.H.R.R. 9 the European Court of Human Rights determined that there were no clear recorded reasons for disagreeing with the SCA decision. There was no explanation why the statutory definition of trafficking did not apply to the individuals and/or why there was no nexus or connection between the trafficking and the offence. This case also highlights the importance of ensuring there is a referral to the NRM in all cases where there are indicators of trafficking or slavery, servitude or forced or compulsory labour. Failure to do so is a breach of Article 4 of the ECHR and the UK’s international obligations under Article 26 of the Anti-trafficking Convention.

Decisions to prosecute whilst awaiting a SCA decision

Once a person has been identified as a potential victim, a decision on whether to prosecute them should, so far as possible, be taken after a SCA decision has been taken. This is particularly important where the suspect is a child. The European Court of Human Rights (ECtHR) held in VCL and AN v United Kingdom (2021) 73 E.H.R.R. 9 that “… in the absence of any assessment of whether they were trafficked and, if so, whether that fact could have any impact on their criminal liability, … pleas [made before such as assessment] were not made “in full awareness of the facts”."

However, each case must be considered in accordance with the Code for Crown Prosecutors on its own facts. If an SCA decision on a suspected victim is pending, paragraph 4.3 of the Code should be considered: the charging decision should only follow all outstanding reasonable lines of inquiry being pursued, unless the prosecutor is satisfied that any further evidence or material is unlikely to affect the application of the Full Code Test, whether in favour of or against a prosecution.

In the limited circumstances where it is appropriate to apply the Threshold Test, there should be a rigorous examination of all five conditions in paragraph 5 of the Code. Scrutiny of each of the conditions is critical to ensuring that cases are not charged prematurely. The decision to apply the Threshold Test must remain under review and the Full Code Test must be applied as soon as the anticipated further material is received.

Stage 2: Is there Clear Evidence of Duress?

At this stage the prosecutor should assess whether evidence of duress means that there is no realistic prospect of conviction.

Duress provides a common law protection for potential victims who commit offences. Prosecutors should be aware that the elements which must be established by a defendant are:

  • the defendant believed that there was a threat of death or serious injury
  • this belief was reasonable, as well as genuinely held
  • the threat was to the suspect, a member of their immediate family, or to a person for whose safety they reasonably regarded themselves as responsible: R v Wright [2000] Crim.L.R. 510, CA; R v Hasan [2005] UKHL 22
  • the suspect’s criminal conduct was directly caused by the threat; and a sober person of reasonable firmness, having the same characteristics as the defendant, would have responded in the same way: R v Graham (1982) 74 Cr App R 235, CA at 241. The characteristics which may be taken into account are only those which realistically make a person less able to resist threats: age and sex may be relevant, as are pregnancy and physical or mental disabilities; other factors are not: R v Bowen [1996] 2 Cr App R 157, CA.

Duress is not available:

  • as a defence to murder, attempted murder (and perhaps to treason involving the death of the sovereign): R v Gotts [1992] 2 AC 412; R v Hasan [2005] UKHL 22 at [21]
  • if there was something the defendant could reasonably have been expected to do, in order to avoid the threat without committing the offence, or
  • where the defendant voluntarily associated with people engaged in criminality, in circumstances where they foresaw or ought reasonably to have foreseen the risk of being subject to violent compulsion: the ‘gang exception’: R v Sharp [1987] QB 853.

Stage 3: Is there Clear Evidence of a Section 45 Defence?

Section 45 of the 2015 Act creates separate statutory defences for adults and children who are victims of modern slavery. The key distinction is there is no requirement for a child to show that they had been compelled to commit the crime, simply that it was as a consequence of them being a victim of slavery or relevant exploitation. In the case of ADG & Another [2023] EWCA Crim 1309 the court in allowing the appeal emphasised the different tests which apply to those who are 18 and over and those under 18 and that the latter is less onerous.

The Modern Slavery Act 2015 only applies to those who commit certain criminal offences after 31 July 2015. Prosecutors should take particular care when dealing with cases in which the offending behaviour covers a period that straddles this implementation date and continue to consider stages 1,2 and 4.

R v CS and Le [2021] EWCA Crim 134 emphasised that careful consideration should be given to the availability of the section 45 defence and whether there is sufficient evidence to disprove the defence beyond reasonable doubt. No charges should be brought if there is sufficient evidence to suggest the suspect is a genuine victim of trafficking or slavery; and that the other conditions in section 45 are met (relevant to whether the suspect is an adult or child); and the offence is not an excluded offence under schedule 4 to the Act. The section 45 defence does not apply to the serious offences detailed in schedule 4 to the 2015 Act.

If the alleged offence is not listed in schedule 4, the prosecutor should assess whether there is sufficient evidence of the defence such that there is no realistic prospect of conviction. However, if the Prosecution can disprove any one of those limbs of the defence, section 45 will not be made out.

Section 45 only places an evidential burden upon the defendant so, to make this defence available, the defendant will only have to adduce sufficient evidence to allow the defence to be considered by the jury. The seriousness of the offences will be a significant consideration when determining what a reasonable person would have done where the defendant is an adult.

If a defendant succeeds in discharging the evidential burden, then the legal burden falls upon the prosecution to disprove the defence beyond reasonable doubt. Where the Defendant puts age in issue, it is for the prosecution to prove beyond reasonable doubt that the defendant is over 18.

The safeguard against “unscrupulous” use of the defence lies within the application of the objective tests set out in section 45(1)(d) (for persons over 18) and section 45(4I) (for persons under 18). In R v MK and Gega [2018] EWCA Crim 667, the Court of Appeal [at paragraph 39] observed that “the prosecution is likely to have less difficulty in establishing to the criminal standard that an adult offender in the defendant’s position had a realistic alternative to committing the offence, than the defendant would have in establishing on the balance of probabilities that a reasonable person in his or her position would have had no realistic alternative but to do what was done.”

Stage 4: Is it in the Public Interest to Prosecute?

If questions two and three (relating to the first stage of the Code for Crown Prosecutors) have been answered in the negative, Prosecutors should go onto consider the second stage of the Code for Crown Prosecutors and decide whether a prosecution is required in the public interest. Prosecutors should apply the factors in the Code for Crown Prosecutors with specific consideration of the following:

  • the seriousness of the offence
  • the level of culpability of the suspect
  • the harm caused to the victim
  • the suspect’s age and maturity

Additionally, Prosecutors should consider the following (see paragraph 20 of VSJ [2017] EWCA Crim 36 and paragraph 76 of GS [2018] EWCA Crim 1824):

  • Whether there is a nexus or connection between the trafficking/slavery or past trafficking/slavery and the alleged offending; and, if so,
  • Whether the force of compulsion from the trafficking/slavery or past trafficking/slavery acting on the suspect is enough to remove their culpability/criminality or reduce their culpability/criminality to a point where it is not in the public interest to prosecute them.

This approach was approved by the ECtHR in the 2021 decision of G.S. v the UK Application no. 7604/19, in which GS unsuccessfully applied to challenge the decision of the Court of Appeal in GS [2018] EWCA Crim 1824.

‘Compulsion’ includes all the means of trafficking defined by the Palermo Protocol. It does not require physical force or constraint.

The means of trafficking/slavery (i.e. the level of compulsion) may not be sufficient to give rise to defences of duress or under section 45 but will be relevant when considering the public interest test.

A suspect’s criminality or culpability should be considered in light of the seriousness of the offence. The more serious the offence, the greater the compulsion needed to reduce the criminality or culpability to the point where it is not in the public interest to prosecute.

When assessing the public interest in respect of a child victim, it is not necessary for there to have been compulsion (VSJ [2017] EWCA Crim 36, paragraph 35). Accordingly, if Stage 4 is reached for a child, prosecutors should consider:

  • whether there is a nexus or connection between the trafficking/slavery or past trafficking/slavery and the alleged offending; and, if so,
  • whether the circumstances remove the child’s culpability/criminality or reduce it to a point where it is not in the public interest to prosecute them. If there was compulsion, then this will reduce the public interest, but it is not a necessary element. As for an adult, the more serious the offence, the stronger the mitigating factors will need to be before it is not in the public interest to prosecute.

Case strategy

The prosecutor’s assessment of whether a suspect is or may be a victim of modern slavery should form part of their case strategy. It might, for instance, address:

  • how the prosecutor has assessed each stage of the four-stage test – what they have considered and how they have reached each conclusion
  • how the prosecutor intends to disprove the section 45 defence, what will need to be kept under review and what further lines of inquiry should be followed
  • if the prosecutor disagrees with the SCA decision, why that is so: “While the prosecutor might not be bound by the findings made in the course of such a trafficking assessment, the prosecutor would need to have clear reasons which are consistent with the definition of trafficking contained in the Palermo Protocol and the Anti-Trafficking Convention for disagreeing with it”: VCL and AN v United Kingdom (2021) 73 E.H.R.R. 9
  • how and why the section 45 defence is likely to be established, and why that means the case cannot proceed
  • how and why, notwithstanding the suspect is or might be a victim of modern slavery, there is no nexus to the offending (applying the relevant statutory test, whether to adult or child), making clear that is the prosecution case and establishing whether this is an issue which the jury will have to decide
  • where the prosecutor considers that the suspect is a victim of modern slavery but the section 45 defence is not available, ensuring this is made clear so the basis of the prosecution is clear in law and the defendant can rely upon it in mitigation if they wish to do so
  • how the Code framework explains and articulates the public interest decision in the case, whether to proceed or not.

Further reading

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