Rendition and extraordinary rendition are not terms defined by law. They describe the process by which a detainee is transferred from one state to another, outside normal legal processes (i.e. extradition, deportation, etc).  In many cases these detainees are transferred to secret detention or to a third country for the purposes of interrogation, often in circumstances where they face a real risk of torture.

The All-Party Parliamentary Group on Extraordinary Rendition was established by Andrew Tyrie in December 2005 in response to allegations that the UK had been involved in the US rendition programme.

In its struggle against international terrorism following 9/11, the United States developed rendition the international transfer of an individual without customary due processes as an instrument of policy. Rendition became associated with the use of coercive interrogation techniques techniques often crossing the threshold of torture, in violation of international standards to which successive American administrations committed themselves.