The report - "Globalizing Torture: CIA Secret Detention and Extraordinary Rendition" - (PDF 216 pages) - states that some 54 countries (including the United Kingdom) offered some level of support for rendition. The United Kingdom is discussed in Section V at para 51.
According to the report, the United Kingdom:
- Assisted in the extraordinary rendition of individuals, gave the CIA intelligence that led to the extraordinary rendition of individuals, interrogated individuals who were later secretly detained and extraordinarily rendered, submitted questions for interrogation of individuals who were secretly detained and extraordinarily rendered, and permitted use of its airspace and airports for flights associated with extraordinary rendition operations.
- Interrogated individuals who were subsequently subjected to secret CIA detention and supplied questions to ask of the CIA’s detainees.
- Provided its airspace and airports for use by flights associated with CIA extraordinary rendition operations. A 2007 European Parliament report “[e]xpresse[d] serious concern about the 170 stopovers made by CIA-operated aircraft at UK airports, which on many occasions came from or were bound for countries linked with extraordinary rendition circuits and the transfer of detainees.” Reports describe Glasgow’s Prestwick airport as a “crucial staging point” in extraordinary rendition circuits. In addition, two British overseas territories, Diego Garcia and the Turks and Caicos, were used by the CIA extraordinary rendition program on various occasions.
The UK has settled a number of law suits but has done so without admission of legal liability. The British government has claimed that it could not defend the cases in court where the principle of 'open justice' basically applies. For this reason, the government is driving the Justice and Security Bill through Parliament so that 'closed material procedure' can be introduced into civil cases. This Bill is discussed in some detail in posts on the Law and Lawyers blog: most recently on 31st January 2013 - Catching up with the Justice and Security Bill.
In the Al Rawi case -  UKSC 34 - the UK Supreme Court ruled that closed material procedure could not be introduced without legislation.
The report presents an appearance of a British government operating with knowledge, connivance, wilful blindness to what was happening to detainees and disregard for basic humanity as well as legally binding conventions to which the UK is a party (e.g. the Torture Convention). The OSJI report presents a case for British Ministers (and former Ministers) to answer but it seems unlikely that they will be called to account by any legal mechanism in the United Kingdom.
The reasons for this lie in the concept of non-justiciability - see Law and Lawyers - Worrying trends ~ No.2 ~ Open Justice Assailed. The 'Detainee Inquiry' set up in July 2010 under the chairmanship of Sir Peter Gibson was discontinued by the British government in January 2012. The report of the Iraq War Inquiry under Sir John Chilcot has been delayed and may not be published until 2014.
The el-Masri case:
The Open Society Foundation reports on the case of Khaled el-Masri in the European Court of Human Right. The court vindicated the long search for justice of Khaled el-Masri, a German citizen who was the victim nine years ago of a mistaken rendition operation by the U.S. Central Intelligence Agency.
In a landmark ruling on Thursday, December 13, the court offered the most comprehensive condemnation to date by any court of what it termed “torture” by the CIA during the campaign of extraordinary rendition of terrorism suspects launched after the September 11 attacks on the United States. The Justice Initiative filed the case on El-Masri's behalf before the court in September 2009. In addition to condemning El-Masri’s arbitrary arrest, detention and interrogation in 2004, the court also found that the so-called “capture shock” techniques used by CIA agents to prepare him for a rendition flight to Afghanistan involved degrading ill-treatment amounting to torture. The ruling further found that El-Masri’s allegations of mistreatment throughout the more than four months he remained in U.S. custody were “established beyond reasonable doubt.”
This case is discussed in some detail in a post on the UK Human Rights Blog - Extraordinary Rendition gets to Strasbourg - a right to the truth - David Hart QC 31st December 2012.