Mutual Legal Assistance Treaties: How Cross-Border Evidence Requests Work

In short: A mutual legal assistance treaty (MLAT) is an agreement between two governments to gather evidence for each other in criminal cases — records, testimony, searches, service of documents and asset freezes. In the United States, the DOJ Office of International Affairs (OIA) is the Central Authority for these requests. An MLAT moves evidence, not defendants; surrendering a person for trial is the job of an extradition treaty. If your records are being sought, an investigation is under way — whether you are a target or a witness, this is the right moment to take advice.

What is a mutual legal assistance treaty (MLAT)?

A mutual legal assistance treaty is a binding agreement in which two countries promise to help each other obtain information and evidence for criminal investigations and prosecutions. Congressional treaty reports describe MLATs as a “formal, streamlined process” for gathering evidence abroad, designed to fit the admissibility rules of the requesting country’s courts.

The first US MLAT, with Switzerland, entered into force in January 1977; the United States is now party to several dozen. Two features set MLATs apart:

• Government-to-government. Requests run between designated Central Authorities, not courts or private parties.
• Dual criminality generally not required. Unlike extradition treaties, most MLATs do not demand that the conduct be a crime in both countries, though some contain an element of it. Requests can usually be refused for political offenses, purely military-law offenses, or where they would prejudice the requested state’s security or essential interests.

How does an MLAT request work to and from the United States?

Every MLAT request to or from the United States passes through the DOJ Office of International Affairs. For outgoing requests, OIA reviews a US prosecutor’s request and transmits it to the foreign Central Authority. For incoming requests, OIA reviews the foreign request and arranges for a US court or agency to execute it under US law.

Outgoing (the US seeks evidence abroad): a prosecutor drafts the request, OIA transmits it, and the requested country executes it under its own law.

Incoming (a foreign state seeks evidence in the US):

1. The foreign Central Authority sends the request to OIA.
2. Where compulsory measures are needed, a government attorney, with DOJ authorization, applies to a federal judge under 18 U.S.C. §3512 (28 U.S.C. §1782 remains an alternative).
3. The judge may issue a search warrant, an order for stored electronic communications, a pen register or trap-and-trace order, or an order compelling testimony or documents — including for related forfeiture, sentencing and restitution proceedings.

Key fact: In the United States, the DOJ Office of International Affairs (OIA) acts as the Central Authority for mutual legal assistance: requests to and from foreign authorities under MLATs and multilateral criminal-assistance conventions run through it.

MLATs generally set no fixed deadline for answering, and in 2018 DOJ itself noted in the Federal Register that OIA’s inventory of pending requests had grown. Execution can be postponed if it would interfere with a domestic investigation, and the requesting state may ask that the request be kept confidential — so the person concerned is often not told.

What kinds of assistance can an MLAT request?

Typical MLAT assistance covers taking testimony, producing documents and records, service of documents, searches and seizures, and locating or identifying persons. Many modern treaties add the transfer of persons in custody to testify, immobilizing assets, forfeiture and restitution. The exact list depends on the specific treaty.

MLATs also limit how the requesting state may use what it receives: material is generally kept confidential and confined to the purposes stated in the request unless the requested state consents.

MLAT vs. letters rogatory vs. extradition vs. Interpol notices

An MLAT gathers evidence; an extradition treaty surrenders a person; a letter rogatory is a court-to-court request used where no treaty applies or by private litigants; an Interpol notice is a police alert to locate a person or share information. All four often appear in the same case, at different stages.

Mechanism	Purpose	Who sends it	US channel	Binding?
MLAT request	Evidence, testimony, asset measures	Government Central Authority	DOJ OIA; foreign requests executed under 18 U.S.C. §3512	Treaty obligation, subject to refusal grounds
Letter rogatory	Evidence or service via a foreign court	A court	Diplomatic channels; foreign requests can be executed under 28 U.S.C. §1782	Discretionary unless an agreement applies
Extradition request	Surrender of a person for trial or sentence	Government	Diplomatic channels; US hearing under 18 U.S.C. §3184	Treaty obligation, subject to treaty defenses
Interpol notice (e.g. Red Notice)	Locate and provisionally arrest, or share information	National police via Interpol	Interpol Washington (US National Central Bureau)	Not an arrest warrant; each country decides its effect

The State Department has advised Congress that letters rogatory can often take a year or more and, absent an international agreement, compliance is a matter of judicial discretion. For surrender itself, see what extradition is and our guide to Interpol Red Notices.

Speak with an extradition lawyer — confidential. Call, WhatsApp or Telegram +357 96 447475, or request a confidential case review.

Can a defendant or private party use an MLAT?

No. MLATs are reserved for government authorities such as prosecutors and investigators, and DOJ states they are not available to private parties, including criminal defendants. Many US MLATs say so expressly: the treaty “shall not give rise to a right on the part of any private person to obtain, suppress, or exclude any evidence, or to impede the execution of a request.”

So a prosecutor can use the treaty to obtain foreign bank records; the defense generally cannot. Alternatives include letters rogatory issued by the trial court (congressional reports note private litigants may continue to use them), voluntary cooperation from witnesses abroad, and, for a party to a proceeding abroad who needs evidence located in the US, 28 U.S.C. §1782. That statute lets a federal court order a person in its district to give testimony or documents for a foreign proceeding, “including criminal investigations conducted before formal accusation,” on a foreign request or the application of “any interested person,” without overriding any legally applicable privilege.

The clause bars invoking the treaty itself; challenges under either state’s domestic law are a separate, fact-specific question.

What if you or your company are the subject of an MLAT request?

If a bank, employer or service provider tells you a foreign authority requested your records — or a US order arrives citing a foreign request — treat it as an early sign of a criminal investigation, in which you may be a target, a subject or a witness. Decisions made now can shape what later becomes a charge, an Interpol notice or an extradition request.

1. Engage counsel before responding. Do not give statements to foreign or US investigators without advice.
2. Identify the case behind the request — which country, which offense, and whether a related US investigation exists.
3. Assert privilege before material is produced.
4. Ask whether any challenge is available. If a US order under §3512 is served on you or your company, counsel can assess whether an objection can be raised before the issuing court; standing is limited and fact-specific.
5. Check the requested state’s law — in many countries execution runs through local courts that may hear affected persons.
6. Prepare for trial use. In US federal trials, foreign business records can be admitted by foreign certification under 18 U.S.C. §3505, and objections generally must be filed before trial.
7. Map the extradition risk. MLAT evidence often supports a later request for extradition to the United States or a foreign request to extradite someone from the US.

Our international criminal defense team coordinates these steps across jurisdictions.

Where do CLOUD Act executive agreements fit?

Under the CLOUD Act (18 U.S.C. §2523), the United States may conclude executive agreements letting a qualifying foreign government send orders for electronic data directly to US service providers, which may then comply without breaching US law, in serious-crime cases, instead of using an MLAT request. Such orders may not intentionally target a US person or anyone located in the United States.

The US–UK agreement, signed in 2019, was the first and entered into force in October 2022; a US–Australia agreement signed in December 2021 entered into force in January 2024. Elsewhere, the MLAT remains the main channel.

Which countries have an MLAT with the United States?

The United States has bilateral MLATs with several dozen countries and also relies on multilateral conventions with assistance provisions. We do not reproduce a list here: relationships change, and an MLAT partner is not always an extradition partner — compare our overview of US extradition treaties. A treaty does not guarantee cooperation; requests can be refused or postponed on treaty grounds.

Treaty relationships change; verify current status against the US State Department “Treaties in Force” before relying on any list. (Updated 2026.)

Speak with an extradition lawyer — confidential. If an MLAT request touches you or your business, call, WhatsApp or Telegram +357 96 447475, or book a confidential case review.

FAQ

What does MLAT stand for?

Mutual legal assistance treaty — an agreement between two governments to gather evidence and give other help in criminal cases. US requests run through the DOJ Office of International Affairs.

Is an MLAT the same as an extradition treaty?

No. An MLAT obtains evidence; an extradition treaty governs surrender of a person. A country can have one with the United States without the other.

Can my lawyer use an MLAT to get evidence for my defense?

Generally not. US MLATs are reserved for government authorities and typically create no right for private persons to obtain, suppress or exclude evidence. Defense counsel usually rely on letters rogatory or voluntary cooperation.

Will I be notified if an MLAT request concerns me?

Not necessarily. The requesting state can ask for confidentiality, and you may learn of it only when a bank, provider or witness is contacted, or an order is served.

What US law lets a judge act on a foreign evidence request?

18 U.S.C. §3512 lets a federal judge, on an authorized DOJ application, issue warrants and orders to execute a foreign request. 28 U.S.C. §1782 separately lets courts assist foreign tribunals, including on letters rogatory.

Does an MLAT request mean I will be extradited?

No — it is evidence gathering, not an arrest warrant. But that evidence can later support charges, an Interpol notice or an extradition request, so seek advice early.