Skip to main content

Accessibility controls

Main content area


Updated: 2 August 2022; 26 April 2023; 24 July 2023|Legal Guidance, International and organised crime


This guidance provides an overview of how prosecutors obtain evidence from overseas for use in criminal investigations or proceedings in England and Wales through bi-lateral co-operation.

For guidance on other types of international cooperation please see: Joint Investigation Teams legal guidance, Proceeds of Crime legal guidance, Extradition - To the UK legal guidance and Extradition - From the UK legal guidance. In addition, the Home Office has produced Mutual Legal Assistance Guidelines for Foreign Authorities for foreign authorities on seeking evidence from the UK.

Key points:

Prosecutorial assistance is not always required to obtain evidence from overseas; often it can be obtained by investigators through police cooperation channels. This is often referred to as informal police-to-police cooperation or mutual administrative assistance (MAA).

In some circumstances it is necessary for prosecutors to obtain evidence located overseas using Mutual Legal Assistance (MLA). This will either be through a formal international Letter of Request (LOR) or for EU Member States, the designated form issued under Article 635 of the EU-UK Trade and Co-operation Agreement (the TCA). This assistance is usually requested by courts or designated prosecutors and is therefore also referred to as ‘judicial cooperation’ the appropriate mechanism to be used to obtain evidence from overseas generally depends on the type of assistance sought and the domestic legislation of the country from which the assistance is required.

Investigators and prosecutors should be alert to the need to obtain evidence from overseas as early as possible and keep this under review as the case progresses.

Using international cooperation

When there is an international dimension to a case, prosecutors may require assistance from overseas authorities, for example to obtain evidence and information to secure the surrender of suspects or defendants, to participate in a Joint Investigation Team (JIT) and/or restrain assets and enforce confiscation orders abroad. The requirement of overseas assistance should be considered as early as possible in the case and form part of the case strategy. The key question to determine whether such assistance is required is whether the assistance constitutes a line of enquiry that is reasonable, necessary, and proportionate, having regard to the factors set out below (issues to consider).

Who should request the evidence?

Evidence located overseas can be obtained in a variety of ways. As stated above, an MLA request is not always required. Wherever possible, police-to-police channels should be used to obtain the assistance.

The requirement to obtain evidence via an MLA request in any given case is determined by the law of the country from whom assistance is sought (the Requested State) and may be dependent upon the nature of the assistance requested, e.g., coercive measures will usually require an MLA request.

Requesting Mutual Legal Assistance (MLA)

Section 7 of the Crime (International Co-operation) Act 2003 (CICA) provides that designated prosecutors and courts (on application of a non-designated prosecuting authority or, where proceedings have been instituted, on behalf of the person charged) can issue an MLA request. Crown Prosecutors are designated under the Crime (International Co-operation) Act 2003 (Designation of Prosecuting Authorities) Order 2004.

Section 7 CICA also states a designated prosecuting authority can only issue a request if:

  • it appears to the authority that an offence has been committed or that there are reasonable grounds for suspecting that an offence has been committed, and
  • the authority has instituted proceedings in respect of the offence in question or it is being investigated

The UK is party to numerous bilateral and multilateral MLA treaties however, there is no requirement for an MLA treaty to exist between the UK and the Requested State to make a request under section 7 of CICA. Where a treaty does exist, this will form the legal basis for requesting assistance and should be cited in the LOR.

Direct or Indirect Transmission

Under section 8 of CICA, MLA requests can be sent directly by a designated prosecutor to the relevant judicial authority in the Requested State. This is known as direct transmission. In practice, direct transmission is only possible where the relevant judicial authority in countries have implemented Article 15 of the 1959 European Convention on Mutual Assistance (as amended by Article 4 of the Second Additional Protocol). However, direct transmission from the UK is not possible for:

  • requests for the transfer of a prisoner to appear in court or assist an investigation
  • requests for bank account monitoring or customer information
  • requests seeking the recognition and enforcement of overseas restraint and/or confiscation orders (see section 74 of the Proceeds of Crime Act 2002)

The European Judicial Network (EJN) Atlas tool allows prosecutors to identify the competent local authority in each EU Member State to receive and execute an MLA request. Other websites, including official government websites of the Requested State may also contain contact information for relevant authorities to receive MLA requests.

All requests which cannot be sent directly overseas must be sent via the UK Central Authority, Home Office, for onward transmission:

UK Central Authority 6th Floor, Fry Building
2 Marsham Street, London, SW1P 4DF

Drafting an MLA Request

An MLA request takes the form of a formal international Letter of Request (LOR), also known as Commissions Rogatoires in civil law jurisdictions. As above, for EU Member States, there is a designated form issued under the TCA. An MLA request is a formal, written legal document that must comply with both domestic statutory requirements as well as any relevant treaty.

An MLA request is a stand-alone document and must be easily understood and capable of execution by the requested state without further consultation and without the need for UK prosecutors or investigators to attend the other country. It is essential that the foreign authority is given all the information it will need to decide whether assistance should be provided. Colloquialisms and jargon should be avoided as should unnecessary use of technical language. It is best to avoid long sentences and lengthy paragraphs. This is particularly important as MLA requests often require translation into the language of the Requested State. The aim is to produce an easy-to-read document which immediately conveys to the reader what is required, why it is required, when it is required by and the form that it is required.

Prosecutors and members of the Government Legal Community can access Country Information pages to obtain information regarding applicable international instruments, translation requirements, and details of where to send the request. This information may also be available on open-source websites or by contacting the Requested State.

Issues to consider

The following is a non-exhaustive list of issues that should be considered when drafting an LOR:

  • Data Protection - Where an LOR contains personal data and is being transmitted outside the EU, the transfer must comply with Chapter 5, Part 3 of the Data Protection Act 2018.
  • Risk Assessments - Where the request appears to engage risk issues because of where it is being sent (for example, a FCDO Human Rights Priority Country), or due to particular information in the request, the Home Office may require a risk assessment to be undertaken before transmitting the LOR to the requested state. For more information, please refer to the website.
  • Timescales – Generally, there is no obligation under international law to execute an LOR within a specific timeframe. For EU countries, however, Article 640 of the TCA, provide timeframes for the acceptance and execution of requests. Prosecutors should be realistic about how long it may take to get a response from an overseas authority. The more unusual, complex, or resource-intensive the request, the longer it may take to execute. Care should be taken to ensure all necessary information to allow the Requested State to action the request is included in the request and that only relevant information is requested to avoid delay. Prosecutors should clearly set out the reason for any urgency in the request (e.g., defendant remanded in custody, immediate risk to individuals, risk of dissipation of assets etc.) and provide the dates of any deadlines to be met.

Confidentiality - In the UK it is standard policy for central and executing authorities to neither confirm nor deny the existence of an MLA request, nor disclose any of its content outside government departments, agencies, the courts, or enforcement agencies without the consent of the requesting authority, except where disclosure is necessary to obtain the co-operation of the witness or other person concerned. Not all overseas authorities adopt a similar approach to confidentiality, therefore CPS prosecutors can also include a paragraph in an MLA request requesting confidentiality to protect unwanted disclosure of the request.

  • Dual Criminality - Some states may not be able to provide assistance if the request arises from conduct which does not constitute an offence in the requested state, particularly where the assistance sought requires the use of a coercive measure (e.g. the search of a property), a conduct-based approach should be taken, i.e., the conduct underlying the alleged offence is considered when assessing dual criminality requirements, rather than seeking to match the exact same term or offence category in both jurisdictions.
  • Translation - Once the LOR is completed it may be necessary to translate it into an official language of the requested country. Prosecutors should check local arrangements regarding the responsibility for arranging and paying for the translation.
  • Costs of Execution - The cost of executing a request is generally borne by the executing authority overseas. Exceptions include costs of an extraordinary nature (which should be agreed in advance) such as payment of the fees and reasonable expenses of expert witnesses, the costs associated with videoconferencing and the costs of transferring persons in custody.
  • Admissibility - Whilst the executing authority will execute the request in line with its domestic laws, the material provided must be admissible according to the law of England and Wales. Prosecutors must take care to include details of any specific procedures required in the MLA request to ensure the material obtained is admissible in any proceedings - for example rights to be read to a suspect in advance of interview.
  • Collateral Use - Under Section 9 of CICA, evidence obtained by the UK may not be used for any purpose other than that specified in the original request without the prior consent of appropriate overseas authority. It is therefore important when drafting the LOR not to unnecessarily limit the purposes to which the evidence obtained may be put.
  • Reciprocity - The UK does not generally require reciprocity but would expect assistance from countries which are parties to relevant bilateral or international agreements with the UK. Reciprocity is required in all requests for assistance in tax matters.

Types of assistance

The extent of assistance which can be provided through informal cooperation varies between countries and is dependent upon factors including:

  • type of assistance sought
  • domestic law of the requested state
  • the existence of applicable legal instruments including treaties and conventions
  • relations between the country concerned and the UK

It is not possible to give a definitive list of enquiries which will always require an MLA request. The following non-exhaustive list notes classes of evidence that usually require an MLA request:

  • banking evidence - obtaining account information and documentary evidence from banks
  • coercive measures - requests for search and seizure and other requests that involve a coercive measure that would require a court order in a domestic case in England and Wales
  • video conferencing links at trial - requesting a link for a witness to give live evidence at a trial in England and Wales from another country
  • witnesses - obtaining a statement from a non-voluntary witness
  • confiscation and restraint of property

Examples of enquiries which can often be undertaken via informal cooperation, rather than MLA, include the following non-exhaustive list of enquiries:

  • previous convictions
  • public Records
  • general intelligence material

The police must always have permission from the receiving country to travel overseas on official business whether on enquiries as a result of an MLA request or for informal enquiries.

Transfer of proceedings

For the purpose of this guidance, transfer of proceedings means a formal request by the CPS to another jurisdiction to take over a prosecution (note separate arrangements exist to transfer reporting a crime).

A formal request for transfer of proceedings is issued by a CPS prosecutor and transmitted overseas by the Home Office. This is not a request for assistance within the meaning of section 7 CICA and there is no domestic legislative basis for transferring proceedings from England and Wales to another jurisdiction, however, several international agreements provide a basis for the transfer of proceedings:

  • Article 21 (Laying of Information) - Council of Europe Convention on Mutual Assistance in Criminal Matters 1959 (1959 Convention)
  • Article 47 - UN Convention against Corruption ('UNCAC')
  • Article 8 - UN Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances ('Vienna Convention')
  • Article 21 - UN Convention against Transnational Organised Crime 2000 ('UNTOC'); or
  • Bilateral MLA / Extradition Treaties

Drafting and transmission

Where a transfer of proceedings is being considered, CPS prosecutors should always contact CPS International Division before any contact is made with the other jurisdiction.

A request to transfer proceedings must be carefully considered and drafted by a prosecutor and addressed to the appropriate overseas authority. In addition, sufficient material should be prepared (and if necessary, translated) to enable the overseas authority to decide whether or not to accept the transfer.

A completed, authorised request (and supporting material) must be submitted to the Home Office (UK Central Authority) for transmission.

If the requested state makes a request for new evidence (i.e., that which was not already gathered or available at the time the transfer request was made) that cannot be fulfilled via police-to-police cooperation, an LOR should be drafted by the overseas authority and sent to the Home Office.

Non-criminal proceedings

The CPS may be asked to assist with overseas enquiries by the police or others where the cooperation does not directly relate to criminal proceedings. In such situations, CICA does not apply, and an MLA request cannot be issued. Instead, a prosecutor may seek assistance from a foreign authority to obtain information or assistance via a standard business letter. The prosecutor should simply and courteously explain the purpose of the request, on whose behalf it is made, what material/assistance is requested and why. As with an MLA request, it must be clear that police-to-police requests or other ways of requesting assistance will not suffice. For example:

  • Inquests - The coroner may have requested information, e.g., a copy of an autopsy report or witness statements, only to be told by the foreign authority that the request must be made by a judicial or prosecution authority. In order to assist the coroner and to ensure the desired outcome, the prosecutor may write to the foreign authority requesting the information. The prosecutor should note in brief the role of the Coroners’ Court in England and Wales, and the purposes to which the supplied information will be put. This course of action should only be taken if it is clear the other country will not respond without prosecutorial assistance and where the coroner has specifically agreed that we make the request on their behalf.
  • Family liaison visits - Ensuring the wellbeing of victims and witnesses is an important part of the CPS’s commitment to victim care and for case management. Occasionally, a foreign authority will only accede to a request for officers to travel overseas for family liaison visits following a formal letter from a judicial or prosecution authority. Where that happens, the prosecutor may send a business letter.


International enquiries are a powerful and often crucial tool in the investigation and prosecution of offences. It is important to note that the approach to disclosure in the international context is consistent with the disclosure principles, including reasonable lines of enquiry as set out in paragraphs 46-54 of the Attorney General's 2022 Guidelines on Disclosure ("International Matters").

Other resources

Further reading

Scroll to top