Double criminality

Double criminality, or dual criminality, is a requirement in the extradition law and international prisoner transfers of many countries. It states that a suspect can be extradited from one country to stand trial for breaking a second country's law only if a similar law exists in the extraditing country, and that any crime in any sentencing country must also be a crime in any other country to receive any internationally transferred prisoners.

If Country A has no laws against blasphemy, for example, a lack of double criminality could prevent a suspect from being extradited from Country A to face blasphemy charges in another country, i.e. no outbound extradition from Country A, and neither are citizens of Country A eligible for international prisoner transfers from another country having criminally convicted them for blasphemy, i.e. no inbound prisoner transfer to Country A.