Mutual legal assistance

Mutual legal assistance (“MLA”) is a formal method of cooperation between countries for obtaining cross-border assistance in the investigation or prosecution of criminal offences. This cooperation can include obtaining and collecting evidence, carrying out searches, freezing assets and making witnesses available for hearings.

MLA is a legal process usually governed by a treaty.  A formal request will be made by a court or prosecutor in the requesting state to seek evidence for use in an ongoing criminal case, which will then be executed in the requested state in accordance with the treaty and its own domestic law.  Often the treaty will provide for ‘central authorities’ or ‘competent authorities’ with responsibility for transmission, receipt and execution of requests.

MLA usually is distinguished from informal or ‘police-to-police’ co-operation, for example through INTERPOL.  A useful distinction, although not one that applies in all circumstances, is that MLA is used for gathering evidence for use in criminal proceedings and/or where a court order is required to obtain the evidence, such as bank records, whereas police-to-police co-operation is used by law enforcement agencies to share information for investigative and intelligence purposes which is already in their possession or which can be obtained voluntarily from its source, such as criminal records.

MLA requests can feature in routine investigations, not just cross-border cases, particularly in relation to banking and electronic evidence which often is not stored in the country in which the offence is being investigated and invariably requires a court order for its production.

The international legal framework

The United Kingdom is party to numerous bi-lateral and multi-lateral mutual legal assistance treaties (“MLATs”) and conventions with the EU, the United States, Japan, China, the Commonwealth and most African and South American countries, among others. The United Kingdom may also assist countries outside of such formal agreements or pursuant to United Nations instruments such as the UN Convention Against Corruption.  An MLAT typically will set out the process for sending and receiving requests, the types of assistance that can be requested, the format for the request and grounds for refusal.

The domestic legal framework

The United Kingdom has a domestic legal framework governing the process for making, receiving, authorising and executing MLA requests.

The key piece of domestic legislation is the Crime (International Cooperation Act 2003 (the 2003 Act’), which implemented seven EU agreements governing MLA in criminal matters. The 2003 Act makes provision for, inter alia, the cross-jurisdictional service of summonses and other procedural documents, the making and receipt of requests to obtain evidence from abroad, the exercise of search and seizure powers overseas, temporary transfer of prisoners, with their consent, to assist in criminal investigations and the facilitation of witnesses giving evidence in overseas proceedings.

The Crime (Overseas Production Order) Act 2019 (‘the 2019 Act’), introduced a new power for UK law enforcement agencies whereby a UK court may issue an overseas production order (‘OPO’) for data stored electronically overseas. OPOs are directly enforceable against a Communications Service Provider based outside the UK and thereby provide an alternative route to obtaining electronic evidence from overseas. The power is contingent on the existence of an international co-operation agreement between the UK and the jurisdiction in which the data is stored that must be designated under the 2019 Act. So far only one such agreement, between the UK and the US, has been so designated.

Further provision is made in Part 11 of the Proceeds of Crime Act 2002 and the Proceeds of Crime Act 2002 (External Requests and Orders) Order 2005, SI 2005/3181 for mutual enforcement of restraint and confiscation orders.

MLA with EU Member States

Before the UK left the EU and before the end of the transition period, the primary instruments governing MLA with Member States were:

The UK’s position with respect to the instruments above and all other avenues of cross-border security and criminal justice cooperation with the EU has been altered by the decision to leave the EU. The future of such cooperation is provided for in the UK-EU Trade and Cooperation Agreement as given effect by the European Union (Future Relationship) Act 2020 (“EUFRA 2020”) which received Royal Assent on 30 December 2020.

UK-EU Trade and Cooperation Agreement

Requests for MLA

Part 3 of the Trade and Cooperation Agreement makes provisions for law enforcement and judicial cooperation in criminal law matters, including MLA.

Under the Agreement, requests for MLA between the UK and the EU are made pursuant to the European Convention on Mutual Assistance in Criminal Matters. The Agreement has sought to replicate the provisions of the EIO, UK access to which was lost on 31 December 2020, subject to transitional arrangements for requests received or transmitted before that date.

The Agreement provides for standard processes and formats for requests and specific timescales for action. The competent authority making the request must be satisfied that it is both necessary and proportionate and that, under the same conditions in a domestic case, the investigative measure or measures sought could be ordered. If the investigative measure sought either does not exist under the domestic law of the requested State or would not be available under the same conditions in a domestic case, the competent authority of that State should consider an alternative measure. The requested State must decide whether to execute the MLA request within 45 days and execution must take place within 90 days. Under the EIO system, requests in respect of evidence already available had to be acted upon within 30 days, or 120 days in cases requiring investigative measures to be undertaken by the requested State.

Other cooperation measures in the Agreement are set out below:

Exchange of DNA, Fingerprints and Vehicle Registration Data (“VRD”)

The Trade and Cooperation Agreement makes provision for the exchange, between the UK and EU Member States, of biometric data through the Prüm database, viz DNA and fingerprints, as well as VRD for law enforcement purposes.

Criminal Records Data

The UK is under a duty to notify, within 28 days, the central authority of the relevant Member State where a citizen of that Member State has been convicted of a crime in the UK, subject to data protection safeguards. The Trade and Cooperation Agreement provides that Member States’ central authorities are under a corresponding duty to notify. The UK may request from any Member State a record of conviction information held by the relevant central authority for the purpose of preventing, investigating, detecting or prosecuting a criminal offence.

Eurojust and Europol

The UK will benefit from ongoing cooperation with Eurojust and Europol as a ‘third country’. The agreement will be supplemented by a working document to be agreed by the UK and each agency. For the purposes of future cooperation the UK is not a member of Eurojust or Europol and so will be unable to directly influence decision making within the agencies.


The UK and the EU have committed to mutual support in the prevention of money laundering and terrorist financing as well as pledging cooperation on asset freezing and confiscation of criminal property in accordance with relevant Conventions.

Jasvinder Nakhwal
Tel: +44 (0) 20 7822 7753

Nick Vamos
Tel: +44 (0) 20 7822 7776