Surrender without a treaty: the legal routes states use

Most people assume a country can hand over a suspect to another state only if the two have signed an extradition treaty. In practice, the position is more flexible. International law does not generally oblige a state to extradite without a treaty, but it does not forbid it either. Many countries have written domestic laws that let them act on other grounds. That flexibility matters because cross-border crime does not follow the map of treaty partners.

Why a treaty is the norm but not the rule

A treaty gives both sides clear obligations: which offences qualify, what evidence is needed, which grounds allow refusal, and how long the process may take. It also gives the requesting state a legal right to ask and the requested state a duty to consider the request in good faith.

Without one, there is generally no binding duty to surrender anyone. Any decision becomes a matter of national law and policy. Extradition without treaty therefore depends on whether the requested state's legislation allows it and whether its government is willing to proceed.

Domestic legislation as the legal basis

Many states have passed laws that stand in for a treaty, at least in part.

• United States. Extradition normally rests on a treaty. However, federal law lets the Secretary of State surrender certain foreign nationals to a country with no treaty where they are accused of a crime of violence against a United States national. The Supreme Court has also held that the executive branch needs legal authority, whether a treaty or a statute, to surrender anyone.
• United Kingdom. The Extradition Act 2003 sets out arrangements for designated territories. It also allows special extradition arrangements to be made for a single case, which lets ministers deal with a request from a state that has no standing agreement with the UK.
• Canada. The Extradition Act allows surrender to be based on a specific agreement for an individual case, so a missing treaty need not end the matter.
• Australia. The Extradition Act 1988 allows a country to be declared an extradition country by regulation, without a bilateral treaty being in place.
• Germany and Switzerland. Their national extradition laws allow requests to be handled without a treaty if the requesting state gives suitable assurances of reciprocity.

Reciprocity and comity

Reciprocity is the promise that the requesting state would treat a similar request from the other side in the same way. It is often given in writing through diplomatic channels. Some national laws make such an assurance a condition of surrender.

Comity is the courtesy and goodwill that states extend to one another, without being legally bound to do so. A government may grant a request because it wants a cooperative relationship, because it shares an interest in suppressing a particular type of crime, or because it expects help in return later. Comity is not a legal right. It explains why a request can succeed even when nothing obliges the requested state to agree.

Multilateral conventions as a substitute

Several widely ratified conventions deal with specific crimes. These include the United Nations Convention against Transnational Organized Crime, the United Nations Convention against Corruption and the international drug-control conventions. Many of them allow a state that makes extradition conditional on a treaty to treat the convention itself as the legal basis when it receives a request from another party. This can bring in countries that have no bilateral agreement with each other, and it is a major route for the surrender of suspects in organised crime, corruption and trafficking cases.

Safeguards that still apply

The absence of a treaty does not remove the usual protections. Courts and ministers in most systems still look at the following.

1. Dual criminality: the conduct must be an offence in both countries.
2. Speciality: the person can be tried only for the offences for which surrender was granted, unless the surrendering state agrees otherwise.
3. Human rights bars: surrender may be refused where there is a real risk of torture, an unfair trial or a death sentence without assurances.
4. Political and nationality exceptions: these vary between states and are often written into the national law.

A person facing a non-treaty request can usually challenge it before a court in the same way as in any other extradition case, although the grounds available depend on the national law.

Other routes: deportation and removal

Where formal extradition is unavailable, states sometimes use immigration powers. A person with no right to stay may be deported or expelled to the country that wants them. This is sometimes called disguised extradition. It can be lawful, but courts may examine whether the immigration process was misused to avoid the safeguards that apply in extradition proceedings.

Forcible abduction is treated differently depending on the court. In the United States v Alvarez-Machain, the United States Supreme Court allowed a trial to go ahead despite the defendant's abduction from Mexico. In Bennett v Horseferry Road Magistrates' Court, the House of Lords took the opposite view for England and Wales, holding that a court may stay proceedings as an abuse of process where the defendant has been brought before it through serious illegality.

What this means in practice

Surrender without a treaty is real but less predictable. It relies on national legislation, diplomatic assurances and the willingness of the requested state to cooperate. Outcomes can depend as much on the relationship between governments as on the legal merits.

For courts, the task is the same as in any extradition case: to check that a lawful basis exists, that the safeguards are met and that the person has had a fair chance to challenge the request. As cross-border crime continues to grow, the combination of domestic statutes, conventions and case-by-case agreements is likely to remain a central part of how suspects are handed over.