Prompted by this question.

For example, officials from Cuba or Iran (or even friendly countries like Taiwan, Ukraine, etc) officials go to US officials, present evidence that one of their nationals committed a crime in the source country then legally (how is irrelevant) entered the US for the long term.

To make it juicy, lets say it was a heinous crime with lots of solid evidence.

Would the US say "sorry, wish we could help, but legally impossible", or could they arrest him and start extradition proceedings anyway (under some legal theory which I'm unaware of)?

  • "how is irrelevant" you will find that even with extradition treaties in place, many countries will not extradite their own citizens to other countries. So it might be very relevant if it includes citizenship.
    – nvoigt
    Commented May 5, 2023 at 6:15
  • @nvoigt the "how" is how the foreign national got into the US.
    – RonJohn
    Commented May 5, 2023 at 7:56
  • All I am saying is that one way to "legally enter the US long term" is gaining citizenship. And since that complicates any answer to your question, you may want to exclude it.
    – nvoigt
    Commented May 5, 2023 at 8:09
  • There are 200 countries, and the US technically has 50 states that have inter-state extradition treaties. There's literally thousands of extradition treaties. Please focus the question some.
    – Trish
    Commented May 5, 2023 at 8:28
  • 1
    @trish "an extrajudicary (outside of the legal framework) process". My question specifically mentions "under some legal theory which I'm unaware of".
    – RonJohn
    Commented May 5, 2023 at 9:42

2 Answers 2


There are circumstances in which countries that are generally recognized to follow the rule of law will extradite in the absence of a treaty.

For example, the U.S. generally will not extradite absent a treaty, and there are many countries with which the U.S. does not have an extradition treaty. Regardless, 18 U.S. Code §§ 3181 and 3184 leave the executive with the authority to extradite

without regard to the existence of a treaty, persons (other than citizens, nationals or permanent residents of the United States), who have committed crimes of violence against nationals of the United States in foreign countries.

U.S. Department of Justice Manual, 9-15.100 - General Principles Related to Obtaining Fugitives from Abroad

  • FWIW, while I can't find a link to a case where this has happened at the moment, I have seen reports of cases where this has indeed happened in the U.S. and in other law abiding countries.
    – ohwilleke
    Commented May 5, 2023 at 21:52

Extradition from the United Kingdom, under the Extradition Act 2003, normally happens in the context of an treaty between the UK and the other country, coupled with an official designation by the UK government of that country as either a "Category 1" or a "Category 2" territory. If there isn't such an agreement, ad-hoc arrangements are still possible for a specific proposed extradition. Section 194 of the Act allows the government to deem that place to be a Category 2 territory (possibly with some modifications to the rules) for the purposes of that request only.

This recently happened for Japan, which wanted to extradite three people from the UK for alleged robbery of a jewellery shop in Tokyo in 2015. This is apparently the first time Japan has proposed such an extradition, and there is no treaty. Instead, the UK government concluded a "memorandum of cooperation" with Japan and issued the certificate required by Section 194. The three people challenged the legality of the UK government's actions in a judicial review, but lost; R (Chappell and Others) v SSHD [2022] EWHC 3281 (Admin).

For an alleged crime which took place outside the UK, it's also possible in some circumstances for an arrest and prosecution to happen in the UK. That is another potential avenue, aside from extradition, where another country passes information to the UK police and hopes that they will proceed.

British law would not allow somebody to be arrested and handed over, other than by the process laid down in statute. It is a basic principle that the state is not allowed to detain people outside of the legal structure. Aside from such statutes as the Habeas Corpus Act 1679, which enacted a general prohibition on the sending of prisoners "into any Parts Garrisons Islands or Places beyond the Seas" and which only another statute could supersede, modern human rights law would not permit this sort of action. In a reverse example, where somebody was abducted from South Africa and brought to the UK outside of a formal extradition process, the House of Lords found that the abduction was such a grave abuse of power that the prosecution could not be allowed to proceed (R v Horseferry Road Magistrates' Court, ex parte Bennett [1994] 1 AC 42).

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