Mutual Legal Assistance: When your assistance is required

This article is an assessment of practical and legal considerations arising from the operation of mutual legal assistance provided by the UK in connection with international criminal investigations.

Mutual legal assistance (MLA) arrangements enable one country to seek assistance in obtaining evidence located in another country for the purposes of criminal investigations or proceedings. In a time when criminal investigations, especially involving fraud or other financial crime, regularly have an international dimension, this type of request is becoming increasingly common. According to the Home Office, the UK has in excess of 12,000 requests at any one time.

Information and documentation that individuals and other entities may be required to provide for transmission overseas may be broad in scope, and, once transmitted, such material may be disclosed to the parties in litigation or potentially made public through the court process. Although companies will want to ensure that they comply with any legal requirement in connection with a criminal investigation, care needs to be taken with respect to professional obligations owed to its clients and customers about whom information may be sought. This article identifies practical considerations for companies and their representatives in the UK who may be required to provide evidence in connection with criminal investigations being undertaken by overseas authorities, along with possible public law challenges by way of judicial review of key decisions.


Any state may request legal assistance from the UK, although such arrangements are likely to be governed by agreements already in place, including multilateral conventions (as between the EU), bilateral treaties (as with the US) and Memoranda of Understanding. In the UK, the provision of co-operation in connection with criminal investigations is determined by the Crime (International Co-operation) Act (CICA) 2003, along with the MLA Guidelines for the UK (the guidelines).

With respect to assistance sought from England and Wales, letters of request are received by the UK Central Authority (UKCA), the central Home Office body acting on the authority of the Secretary of State, which has the function of arranging the execution of MLA requests and transmitting the material obtained to the requesting state.

Alongside the scheme of co-operation established with respect to criminal investigations under CICA 2003, the Financial Services Authority (FSA) is a party to a multilateral agreement setting out the terms of co-operation between financial regulators in sharing information relevant to derivative and securities violations, including market abuse and fraud. This route of information sharing by the FSA, which may be used in connection with either civil enforcement or criminal prosecution, is provided for under s169 of the Financial Services and Markets Act (FSMA) 2000 (International Organisation of Securities Commissions Multilateral Memorandum of Understanding Concerning Consultation and Cooperation and the Exchange of Information).

The type of evidence sought will depend on the use to which it will be put and the requesting state’s own domestic evidential standards. Once the decision has been made to provide assistance in the UK, several measures are available for securing evidence on both a voluntary or compulsory basis, including:

  • Interview and signed statement: where the requesting state does not require evidence given under oath, a witness will be invited to attend an interview on a voluntary basis and provide a signed statement.
  • Witness evidence under oath: the witness will be asked or summonsed to give oral or written evidence, or produce relevant documents under oath at a nominated court (currently the City of Westminster Magistrates Court in London). The court dealing with the request has the same powers as it would for domestic proceedings, including compelling the witness to attend.
  • Compulsory interviews: in cases involving serious and complex fraud, the Secretary of State will pass on the request to the director of the Serious Fraud Office (SFO) rather than a court receiving the evidence. The SFO may exercise its powers to compel witnesses to attend interview and produce documents in accordance with s2 of the Criminal Justice Act 1987 in response to the letter of request. Similar powers are available to the FSA under s165 and s173 of FSMA 2000.
  • Production orders and search and seizure orders: the investigating authority, including the SFO, may apply to the court for either a production order or a search warrant with respect to material requested (including telecommunication or banking evidence). Search and seizure orders must be justified on the grounds to believe that evidence would otherwise be compromised.


In cases where material has been seized or a third party has become aware of the provision of material that may affect their interests, any action must be taken immediately, given there is no fixed period before which material will be transmitted to the requesting state formally by the Secretary of State and, in the meantime, information may be passed to the overseas authority.

A witness in any domestic proceedings has limited control over the way in which information is disclosed in the litigation process, but this will be compounded where material is provided to another jurisdiction. Not only will different rules apply with respect to the disclosure of information and the extent to which proceedings are public, there may be legal or practical difficulties in intervening in the litigation process should the need arise.

The extent to which material obtained through MLA in connection with a criminal investigation may be used in civil proceedings will depend on the agreements in place between the states involved and the legislative rules applicable where the evidence is to be deployed. Although the guidelines confirm that overseas authorities must seek permission to use material for any other purpose than that specified, those affected by the transmission of material are unlikely to have influence over whether this permission is given.

In parallel to the formal route of transmission via the Secretary of State, it is important to be aware that information arising from the processes undertaken in the UK may be passed to the requesting state directly, with the consent of the UKCA. Officers from the relevant foreign authority may attend interviews and the execution of search and seizure orders, although in both cases, this must be requested by the overseas authority in advance with reasons. Further, in R v Secretary of State for the Home Department Ex p Finninvest SPA [1997], the High Court held that information passed by Italian police officers who had reviewed material seized in the UK to their superiors in Italy, prior to formal transmission, did not amount to the ‘transmission of evidence’ under s4(5) of the CICA 2003 Act and was permissible in the circumstances. Therefore, where there is participation of foreign officers in UK processes, assurances may also need to be obtained by the UK authority concerning material being recorded and passed on outside the formal transmission process.


In light of the above, both witnesses or third parties may wish to actively engage in the process to ensure that their interests are protected – most particularly, to ensure that information or documentation obtained and subsequently transmitted is limited to that which is both relevant and necessary.

There are several administrative decisions made during the MLA process that are susceptible to judicial review; these include the decision of the Secretary of State to provide assistance to the overseas authority, the way in which the evidence requested is obtained by the relevant UK authority, and the nature and extent of material that is subsequently transmitted. The key judicial decisions to date have related to the search and seizure warrants obtained by the director of the SFO in response to requests for assistance under CICA 2003, and they provide important guidance with respect to the court’s approach to provision of legal assistance in this country.

In accordance with s14 of CICA 2003, once the Secretary of State is satisfied that criminal or administrative investigation or proceedings are taking place in the requesting state, and there are reasonable grounds to suspect that an offence has been committed in that state, the Secretary of State may authorise provision of the assistance requested. However, once assistance has been authorised, for good reason, it is not the role of the Secretary of State to second guess the information provided in the letter of request or the way in which the investigation is being conducted by the overseas authority. As stated by Tuckey LJ in the case of Abacha & ors v Secretary Of State For Home Department [2001]:

‘The exercise which the Secretary of State has to perform should be simple. He is not required to conduct a criminal trial on paper or to decide disputed questions of foreign law before making his decision.’

Although there are limited grounds on which to challenge the decision to assist, those providing information or documents can have a role in ensuring that the material transmitted is relevant to the investigation being undertaken. The ability to make this assessment depends on access to the information contained within the letter of request, which details the purpose for which assistance is sought, the description of the offences under investigation or charged and a summary of the facts giving rise to the request.

The guidelines confirm the UKCA’s general policy that it will neither ‘confirm nor deny’ the existence of a letter of request – but it will disclose the contents of a request to the extent necessary to secure the co-operation of a witness. In Energy Financing Team Ltd & ors v The Director of the SFO [2005], the Administrative Court confirmed that those affected through the seizure of material did have a right to be satisfied as to the legality of the procedure that led to the execution of the search warrant on the basis that:

‘Judicial control by way of judicial review cannot operate effectively unless the person or persons affected are put in a position to take meaningful advice.’

Therefore, on the grounds of procedural fairness, it may be possible to seek basic details concerning the investigation, for example the nature of the offences under investigation and period of time being considered, sufficient to identify particular information or documents that fall outside the request. Further, for reasons of simple practicality, it should also be possible to obtain the list of questions or specific documents to provide ahead of attending an interview or court to provide evidence.

In circumstances where a search warrant has been executed, given the nature of the process, more material will have been seized as is strictly relevant or necessary. The courts have taken a very pragmatic view of the way in which searches are undertaken to give fullest effect to the agreements to co-operate underpinning the formal MLA arrangements. However, it should again be possible to ensure that any irrelevant material is returned rather than being transmitted.

The starting point with respect to the execution of search warrants is set out in the case of Finninvest SPA, which related to the assistance provided by the SFO to Italian authorities investigating widespread fraud. In Finnivest the High Court made it clear that the powers available to the SFO should not be any more limited simply because they were exercised within the context of a MLA request. Further, the court confirmed that despite the reference to ‘evidence’ within CICA 2003, within the context of an investigation, this necessarily constituted a wider range of documents than would normally be understood by this term. In Energy Financing Team, again relating to the execution of a search warrant by the SFO at the request of overseas authorities, the Divisional Court held that it was a matter for the director of the SFO to decide how best to give effect to the request, which may even include going beyond the terms of the letter of request. The court did concede that that the UK investigatory authority is still responsible for ensuring the warrant is sufficiently narrow so as not to amount to an unlawful fishing expedition.

In such cases it seems that the most practical means of ensuring that irrelevant material is not transmitted to the requesting state is to engage directly with the relevant UK investigating authority. This approach to ‘excise inappropriate material’ was endorsed in Finninvest. However, although certain documents may be clearly irrelevant by virtue of their source or date, it is likely that the courts will take an inclusive view of relevance. As stated by the High Court, ‘relevance cannot be determined when the issues in criminal proceedings have yet to be determined’ (Faisaltex Ltd & ors v Lancashire Constabulary & anor [2009]).


A witness is not required to provide material subject to legal professional privilege (LPP) to any UK authority in accordance with a letter of request, whether the information or documents are sought through voluntary or compulsory powers. Where LPP material has been seized, existing procedures for independent counsel to sift material and return such material will be utilised. However, different considerations will apply with respect to confidential material.

The operation of Article 8 of the European Convention on Human Rights (ECHR) will necessarily be relevant to the provision of material in the context of MLA. This protects individuals from interference by the state in their private life, other than in accordance with several legitimate public interests, including public safety, the prevention of disorder or crime, and the protection of the rights and freedoms of others. Those UK authorities involved in providing MLA must have regard to these interests and, if necessary, undertake the balancing act to determine whether the interference involved in the criminal investigation is proportionate. However, given the public interest involved in the investigation and prosecution of crime, the corresponding interest of the individual will need to be significant – for example, the material is subject to particular duties of secrecy.

In R (on the application of) Hafner & ors v City of Westminster’s Court & anor [2008], a third party solicitor and their firm challenged the decision made by the nominated court that their Article 8 (ECHR) rights were not engaged with respect to professional correspondence to be transmitted. The Administrative Court clarified that correspondence of a ‘business character’ was not excluded from the protection of Article 8. Importantly, it confirmed that although it was for the nominated court to decide on the appropriate procedure to undertake the balancing exercise required by Article 8:

‘In so doing the court will consider whether to give notice of the application to and to hear submissions from any person whose Article 8 rights will be or may be infringed by giving effect to the application.’


MLA may be requested with respect to obtaining evidence from both individuals or entities identified as witnesses in the proceedings, as well as suspects. For this reason, it is important to consider the place of the privilege against self incrimination within the range of assistance provided by the UK. Although individuals invited to attend interview or summonsed to attend court are able to rely on this privilege, different considerations apply with respect to the powers available to the SFO and FSA to compel a witness to answer questions. In recognition of the fact that the witness is not able to refuse to answer questions on the basis of self incrimination, the European Court of Human Rights confirmed in Saunders v the UK [1996] that answers given cannot be used against the individual interviewed in criminal proceedings, other than in very narrow circumstances. In recognition of these rights, when providing assistance to overseas authorities, before transmitting evidence obtained by compulsory questioning and before answering questions, it is important to ensure that the SFO has obtained an undertaking from the requesting state that it will not be used against the maker of the statement in any prosecution.

By Emily Carter, senior associate, with assistance from Katherine Buckle, Kingsley Napley LLP.


Future of mutual legal assistance (MLA): European Evidence Warrant

Within the EU, the process has commenced to simplify and streamline cross-border investigations by replacing the current processes for MLA with instruments enabling the mutual legal recognition of investigatory powers. The European Evidence Warrant (EEW) was established in 2008 to enable the issuing state to obtain pre-existing ‘objects, documents and data’ from another state. Its implementation is now currently on hold while consideration is given to the complete replacement of the various MLA processes within Europe, including interviewing witnesses, taking statements, intercepting communications and surveillance, with a single comprehensive means of mutual recognition, known as the European Investigation Order (EIO). The operation of the EIO is summarised in Article 8(1) of the European Council’s proposed directive, which states that the executing authority shall recognise an EIO ‘without any further formality being required’, and shall execute the order in the same way as if it had been a domestic order. Although the execution of such orders would still be able to be challenged on grounds of interference with European Convention of Human Rights (ECHR) rights, given the limited discretion exercised within this process of ‘recognition’, the availability of other public law grounds of judicial review may be limited further.