Extradition Treaty Requirements: How the Process Works

Author: Thomas R. Hendricks, Senior Legal Content Specialist |
Reviewed by: Dr. Maria Chen, International Law Consultant |
Last Updated: January 15, 2025

An extradition treaty creates a legal framework under which one country may request the surrender of a person from another country for prosecution or enforcement of a criminal sentence.

However, the existence of a treaty does not mean extradition is automatic. The requesting state must satisfy the conditions contained in the applicable treaty, while the requested state must also apply its own extradition law and any relevant human-rights obligations.

There is no single set of requirements that applies to every extradition treaty. The exact test depends on the agreement in force between the two countries, any applicable multilateral convention and the domestic law of the requested state.

What Does an Extradition Treaty Regulate?

An extradition treaty usually defines the legal conditions under which surrender may take place.

Depending on the agreement, it may regulate:

• which offences are extraditable;
• minimum penalty thresholds;
• dual criminality;
• the documents required with a request;
• provisional arrest;
• nationality restrictions;
• political or military offence exceptions;
• double jeopardy or limitation issues;
• the rule of speciality; and
• the procedure for surrender after extradition is approved.

The treaty should therefore be read together with the domestic law of the requested country. A treaty creates the international legal basis for cooperation, but national authorities still have to decide whether the individual request satisfies the applicable requirements.

What Is Dual Criminality?

Dual criminality means that the conduct underlying the extradition request must constitute a criminal offence in both the requesting and requested states.

The two countries do not necessarily need to use the same offence name or define every element in identical terms. The central question is usually whether the underlying conduct would be criminal in both jurisdictions.

For example, Article 2 of the European Convention on Extradition applies to offences punishable under the laws of both states and also sets minimum penalty requirements.

The exact dual-criminality test can differ between treaties, so it should not be treated as a universal formula.

Do Extradition Treaties Require a Minimum Sentence?

Many do.

Treaties frequently limit extradition to offences serious enough to meet a minimum punishment threshold.

Under the European Convention on Extradition, for example, the offence must generally be punishable in both states by a maximum term of at least one year or a more severe penalty. Where extradition is requested to enforce an existing sentence, the Convention applies a separate minimum sentence requirement.

Other treaties may use different thresholds.

This is why an offence should never be assumed to be extraditable simply because it exists under both countries’ criminal laws.

What Documents Are Required for an Extradition Request?

The required documents depend on the treaty and the law of the requested state.

A formal request commonly includes material establishing:

• the identity of the requested person;
• the offence alleged or the conviction obtained;
• the underlying arrest warrant or judicial decision;
• the relevant criminal-law provisions;
• a description of the alleged conduct; and
• evidence or supporting material required by the applicable treaty.

Some treaties impose detailed evidentiary requirements, while others operate under simplified or different standards.

In U.S. treaty-based extradition proceedings, 18 U.S.C. § 3184 provides for a judicial hearing at which the evidence is considered and, if sufficient under the applicable treaty or convention, the case may be certified to the Secretary of State.

That U.S. procedure should not be treated as a universal model for every country.

What Is Provisional Arrest?

Many extradition treaties allow a requesting country to seek provisional arrest before the complete extradition request has been submitted.

This mechanism is generally used where the requested person may abscond and the formal extradition documents are still being prepared.

The treaty usually determines:

• what information must accompany the provisional-arrest request;
• which authority receives it;
• how long the person can be held before the formal request arrives; and
• what happens if the required documents are not submitted within the prescribed period.

Where an INTERPOL Red Notice is involved, it may help authorities locate a wanted person, but the Notice does not itself replace the treaty or the national legal basis required for extradition.

What Is the Rule of Speciality?

The rule of speciality limits what the requesting country may do after a person has been extradited.

In general, the requesting state cannot simply use extradition for one offence and then prosecute or detain the person for unrelated earlier conduct without satisfying the exceptions provided by the applicable treaty.

Article 14 of the European Convention on Extradition is one example of the speciality rule.

The exact scope of the protection varies between legal instruments, and some systems allow the requested state or the extradited person to consent to broader proceedings.

When Can Extradition Be Refused Despite a Treaty?

An extradition treaty creates a mechanism for surrender, but it can also contain grounds on which surrender must or may be refused.

Depending on the applicable framework, these may concern:

• political offences or politically motivated requests;
• offences that are exclusively military in character;
• nationality;
• previous trial or punishment for the same conduct;
• expiry of relevant limitation periods;
• insufficient treaty documentation;
• death-penalty concerns;
• human-rights risks; or
• failure to satisfy the treaty’s offence requirements.

For example, the European Convention on Extradition contains a political-offence exception and also allows states to refuse extradition of their own nationals, subject to the declarations and domestic rules applicable to each state.

These rules are highly treaty-specific. A refusal ground available under one agreement may not exist in the same form under another.

Does an Extradition Treaty Guarantee Surrender?

No.

A treaty means that a legal framework exists for considering an extradition request. It does not guarantee that the person will ultimately be surrendered.

Authorities still need to determine whether the request satisfies the treaty, domestic legislation and any applicable constitutional or human-rights safeguards.

This is one of the main reasons why treaty status alone cannot answer whether extradition will occur in a particular case.

Can Extradition Take Place Without a Treaty?

Sometimes.

The legal position depends on the requested country.

Under U.S. law, extradition is generally treaty-based, subject to a narrow statutory exception for certain cases involving crimes of violence against U.S. nationals abroad. The U.S. Department of Justice also notes that some other countries permit extradition without a treaty, including on the basis of reciprocity.

A multilateral convention or another statutory mechanism may also provide a legal basis in some jurisdictions.

For this reason, “no bilateral extradition treaty” should not automatically be interpreted as “extradition is impossible.”

Are EU Extradition Cases Governed by Treaties?

Between EU Member States, the European Arrest Warrant has replaced the traditional extradition system.

The EAW is a judicial surrender mechanism based on mutual recognition rather than a conventional bilateral extradition request. EU judicial authorities recognise and execute warrants issued by other Member States subject to the rules in Framework Decision 2002/584/JHA.

This means that an EU-to-EU surrender case should not automatically be analysed under the same procedure as a traditional treaty-based extradition case involving a non-EU country.

How Should an Extradition Treaty Be Analysed?

The correct starting point is the specific relationship between the requesting and requested countries.

A legal review should establish:

1. which treaty, convention or other legal instrument is currently in force;
2. whether the alleged offence satisfies the extraditable-offence test;
3. whether dual criminality is required and satisfied;
4. whether the required warrant, judgment and supporting documents exist;
5. whether any mandatory or discretionary refusal grounds apply;
6. whether nationality changes the legal position;
7. whether speciality or other post-surrender protections apply; and
8. how the treaty interacts with the domestic law of the requested state.

Only after those questions are answered can the legal effect of the extradition request be assessed properly.