The laundering of the proceeds of corruption does not stop at borders. Nor then can the investigation and prosecution of corruption. Countries require the assistance of the judicial and investigatory authorities of other states to investigate corruption, prosecute offenders and recover corruptly acquired assets.


Mutual legal assistance is the formal mechanism by which countries request and provide assistance in obtaining evidence in one country to assist in criminal investigations or proceedings in another. It is also the mechanism by which an order from one state confiscating or forfeiting the proceeds of corruption may be enforced in another.

A request for assistance is made by a legal document, known in some jurisdictions as a letter of request, in others as a commission rogatoire or letters rogatory.

Mutual legal assistance should be distinguished from obtaining intelligence, for example, locating those suspected of crimes. Obtaining intelligence is not the subject of this note, although it should be emphasised that evidence valuable to an investigation or prosecution can sometimes be obtained by seeking the informal assistance of foreign agencies designated to deal with letters of request, or by direct searches of publicly available databases, or by instructing lawyers or other agents to do so.

This guidance note is intended to give an overview of mutual legal assistance, and to provide some practical guidance on how to make requests that will have the best chance of quickly providing the information required to investigate and prosecute cross-border crime.

What is the legal basis for a letter of request?

Requests for mutual legal assistance are usually made under various inter-state treaties, schemes and conventions. Examples include the United Nations Convention Against Corruption and the Commonwealth Scheme Relating to Mutual Assistance in Criminal Matters (the Harare Scheme). Article 46 of UNCAC requires states to provide each other with the widest measure of mutual legal assistance in investigations, prosecutions and judicial proceedings in relation to corruption offences.

Some foreign countries are able to execute a letter of request even in the absence of any formal arrangements between the receiving and requesting states. The United Kingdom, for example, can provide most forms of assistance without bilateral or international agreements.

What help can be provided?

The evidence that can be obtained through a request for mutual legal assistance will vary from country to country. Available assistance may include:

  • obtaining documentary evidence held by offenders or third parties;
  • in particular obtaining banking documentation including, for example, bank statements, payment instructions, account opening forms and know your customer information;
  • tracing, freezing and confiscation of the proceeds of corruption, including enforcement of domestic confiscation orders;
  • use of domestic investigatory powers;
  • exercise of powers to search premises and seize relevant documents;
  • service of legal documents;
  • obtaining witness statements on oath;
  • arranging for evidence to be given by video-conference;
  • interception of telephone communications;
  • temporary transfer of prisoners to assist with criminal investigations and proceedings, but usually only if they consent;
  • the creation of a Joint Investigation Team, including police or prosecutors from both the sending and receiving states, to investigate particular crimes.

Who deals with requests for mutual legal assistance?

In most countries, requests for mutual legal assistance are received and co-ordinated by a designated "central authority".

The extent of involvement of the central authority varies from country to country. Some are nothing more than post-boxes, distributing the request to the relevant law enforcement organisation, with no involvement in deciding whether to execute a letter of request, or in actually executing it. Others take a much more active role in ensuring that requests for mutual legal assistance conform to the requirements of domestic and international law, in clarifying any ambiguities with the requesting state and in co-ordinating the execution of a request.

Typically, the costs of executing a MLA request are borne by the receiving state.

Why would a request be refused?

There are a number of reasons why a request for mutual legal assistance may be refused. These will vary from country to country. The golden rule is to check with the central authority of the receiving state: they will be able to tell you if something can be done, or put you in touch with an agency that can provide the information.

Examples of potential reasons for refusing a request include:

  • lack of reciprocity of arrangements between requesting and receiving states;
  • the evidence requested cannot be lawfully gathered in the receiving state;
  • the offence being investigated or prosecuted would not be an offence under the laws of the receiving state;
  • the proceedings are political in nature;
  • the offender has been convicted or acquitted of an offence arising from the same facts in the receiving state;
  • national security;
  • the criminal investigation or proceedings is based on the offender's race, religion, nationality or political opinions.

Making a request – good practice

We will now discuss good practice in making a letter of request. Some preliminary points:

  • It is vital that a letter of request is in the form required by the receiving state and contains all of the information required by the receiving state to execute a request for assistance efficiently.
  • Many central authorities will publish notes on how letters of request should be drafted, and may even publish pro-forma drafts. If so, follow the guidance or format as closely as possible. For example in the United Kingdom the Home Office web-site has detailed guidelines (
  • Letters of requests are formal legal documents. However, the intention of the author should be to produce a document that is easy to read and tells the receiving state what evidence is required, why, when and in what format.
  • It is good practice to make a request as a stand-alone document, with any supporting documentation appended and indexed wherever possible.
  • Make requests as early as possible, provided the criteria required by the receiving state to consent to a request are met. Do not forget that requests can be made in support of a criminal investigation.
  • Ensure that the country that is asked to provide evidence knows in what form it should be provided. The receiving state cannot be expected to know whether, for example, a witness statement needs to be in a particular form or that the documents being sent must be accompanied by a certificate verifying them as genuine.

For example, a well-drafted letter of request may:

  • state that the sender of the request has authority to make it, and under what legislation;
  • give the names of the person conducting the investigation or prosecution, with full contact details;
  • state the treaty, convention or scheme that the request is being made under and the obligations of the receiving state under those arrangements;
  • provide any necessary assurances required by the requesting state, for example, that a criminal investigation or prosecution is ongoing, or that any evidence provided will only be used for the purposes of a criminal investigation or prosecution;
  • identify the defendant and other names that he or she uses;
  • explain the purpose of the request;
  • describe the offences under investigation, or the charges that have been brought, and describe and attach the legislation that criminalises the conduct and explains the penalties;
  • summarise the facts giving rise to the request in a clear and logical order, and explain why there are reasonable grounds to conclude that an offence has been committed;
  • summarise the present position in the investigation or prosecution and identify any deadlines or particular reasons for urgency;
  • describe the evidence or other assistance required;
  • explain the purpose for which the evidence or assistance is required and its relevance to the investigation or proceedings;
  • explain any particular procedures to be followed in executing the request that are essential under the domestic law of the requesting state, for example, the manner in which any statement is to be taken and recorded, whether certification of documents is required, or whether original documents or copies are required;
  • state the identity, date of birth and location of any person from whom evidence is required and, ideally, set out the questions they should be asked;
  • give precise descriptions of any property to be searched, full details of the material to be seized, why it is material to the investigation or proceedings, why it is thought that it is located at the property and why it is thought that the person holding it would not produce it at Court if ordered to do so;
  • give precise details of any property to be frozen or confiscated, the link between it and the offender and details and certified copies of any domestic Court orders freezing or confiscating the property in the requesting state;
  • set out any other information which may facilitate execution of the request;
  • be signed – very important and sometimes overlooked.

Informal requests and civil proceedings

It is worth considering whether the required evidence can be obtained informally and quickly. By informally, we mean asking the central authority (or other agency if appropriate) of a foreign country for assistance without issuing a formal letter of request, or obtaining the information directly from publicly available databases, or by instructing solicitors or others to obtain the information for you.

Clearly, there will be circumstances in which a formal letter of request is essential. For example:

  • evidence might be required from a non-cooperative witness;
  • documents may need to be obtained by compulsion, for example, details of bank accounts and transfers or know your customer information from financial institutions;
  • a search and seizure order may be sought.

All these are examples where there will be a need for the exercise of coercive powers by the authorities of the receiving state. In these circumstances a formal letter of request will certainly be required.

However, there are numerous examples where coercive power is not required to obtain documents because documents are in the public domain or the authorities are able to action a request without invoking legal mechanisms. For example:

  • In many countries, like the United Kingdom and United States, a great deal of information about the ownership of property (usually including the price paid for it) can be obtained quickly from a central Land Registry for a small fee.
  • All jurisdictions maintain company registries which retain varying amounts of information, for example, copies of audited accounts, and details of directors and share-holders.
  • Potential witnesses willing to assist voluntarily could be approached directly, provided that is lawful in the country in which the witness is located. Receiving states (or other organisations such as Interpol) may assist in taking statements on oath from witnesses willing to help.

Many countries are willing to deal with informal requests, although countries differ in the extent to which information can be provided informally. The willingness to deal with informal requests will depend on the domestic laws of the receiving state, the strength of the relations between the requesting and receiving states and, of course, the attitude of the individuals who receive and are asked to deal with an informal request. Building relationships with individuals in central authorities can be very helpful.

Sometimes, information is sought informally from Government agencies in the receiving state without involving its central authority. It is vital to ensure that any such request is made and carried out lawfully and that the central authority has no objection. If not, the evidence obtained may have little value and the relationship with the central authority may be damaged, possibly hindering efficient execution of future letters of request.

Speed of response

For mutual legal assistance requests to be effective to gather information and evidence, they often need to be sent and executed quickly. Good co-operation is needed between the criminal practitioners of the sending and receiving states. There has been considerable criticism in some corruption cases that mutual legal assistance has been too slow and cumbersome a process, ultimately preventing timely prosecutions or recovery of assets. It is also true that there have been a number of cases where success has been achieved because of efficient and effective mutual legal assistance.

If mutual legal assistance is not likely to be an effective and efficient tool to restrain corruptly acquired assets, obtain evidence and eventually to make recoveries, it will be worth considering whether civil proceedings should be brought separately in the receiving state to freeze or recover property. In some circumstances, civil proceedings can be a more effective mechanism for making recoveries. Civil orders freezing property can sometimes be obtained very quickly by states, and it may also be possible to obtain evidence from third parties such as banks used by the offender. For more information, see our guidance note "Civil amd criminal mechanism to recover the proceeds of corruption" and "Recovering corruptly acquired assets laundered to or through the UK"?

Use of evidence obtained through mutual legal assistance

Unless already in the public domain, evidence obtained through mutual legal assistance can usually only be used for the purpose of the criminal investigation or proceedings for which it has been obtained and not, for example, in civil proceedings to recover corruptly acquired assets. Some states are, however, able to give permission for the use of evidence in civil proceedings, or for civil forfeiture proceedings. Other states have no legal power to give permission. However, evidence may sometimes enter the public domain as a result of a trial or other hearing in public, or possibly at an earlier stage, and this may remove the bar to its use in other proceedings.

United Nations Office on Drugs and Crime (UNODC)

The UN Office on Drugs and Crime (UNODC) has developed a software programme: MLA Request Writer Tool. It is intended to be a simple tool to assist States to draft requests with a view to facilitate and strengthen international cooperation.

The drafting tool guides casework practitioners through requests with a series of templates. Caseworkers fill in the various data fields and select drop-down menus in each template in order to make requests. When completed, the programme will automatically generate a correct, complete and effective request. The programme also gives access to relevant multilateral, bilateral and regional treaties and agreements and national laws and includes a case management tracking system for incoming and outgoing mutual legal assistance requests.

The tool is available on written request to the United Nations Office on Drugs and Crime, Legal Advisory Programme, Post Office Box 500, A-1400, Vienna, Austria

The UNODC web-site contains helpful information on drafting MLA requests. It has a specific page on the MLA Request Writer Tool at

Concluding remarks

We emphasise a few key points that run throughout this paper:

  • try to discuss an intended request for mutual legal assistance with the receiving state before issuing it – doing so significantly increases the likelihood of making a request that complies with their needs and will be dealt with efficiently;
  • make requests early, execution sometimes takes time; be clear and precise;
  • tell the receiving state what you need, by when and in what format;
  • where mutual legal assistance may not be efficient, consider whether the information you need or the objectives you have will be more quickly met by either an informal request for assistance or through civil proceedings.