MI6

Richard Tomlinson joined back in 1991 then left, persona non grata. They put him in prison for his pains. He says they are a dodgy lot. See MI6: Inside the Covert World of Her Majesty's Secret Intelligence - Uncensored. The uncensored version [ Brown and Mandelson ] is the interesting one. The red bits were censored. They finger Robin Cook - fornication, Brown - queer, Mandelson - ditto, Hague - ditto, Coe - ditto.

MI6 Operations - http://www.guardian.co.uk/world/2012/feb/14/mi6-licence-to-kill-and-torture - acts of state
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In fiction, James Bond drew quite judiciously upon his licence to kill, bumping off just 38 adversaries in a dozen Ian Fleming novels. In each case, the individual received his or her just deserts. In real life, MI6 insists its officers do not kill anyone. "Assassination," its former head Sir Richard Dearlove has said, "is no part of the policy of Her Majesty's government" and would be entirely contrary to the agency's ethos.

But there can be circumstances in which MI6 officers do have a licence to kill or commit any other crime, enshrined in a curious and little-known law that was intended to protect British spies from being prosecuted or sued in the UK after committing crimes abroad. Section 7 of the 1994 Intelligence Services Act offers protection not only to spies involved in bugging or bribery, but also to any who become embroiled in far more serious matters, such as murder, kidnap or torture – as long as their actions have been authorised in writing by a secretary of state.

And as such, the section is certain to come under intense scrutiny in the months ahead, as detectives and human rights lawyers pore over the details of the secret rendition operations that MI6 ran in co-operation with Muammar Gaddafi's regime in 2004. Last month Scotland Yard and the Crown Prosecution Service announced that the operations, in which two leading Libyan dissidents were abducted and taken to Tripoli with their families, were to be the subject of a criminal investigation. A few days later lawyers for both families began civil proceedings against Sir Mark Allen, the former head of counter-terrorism at MI6, accusing him of complicity in their "extraordinary rendition", torture and inhuman and degrading treatment. Proceedings against the government, MI6 and MI5 are to follow.
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The Grauniad is annoyed about MI6 having a let out clause which allows its men to to carry out Acts of State. They do not mention that Mossad and other vicious thugs in Israel do this kind of thing all the time.

 

What Is An Act Of State? Definition And Meaning
QUOTE
Executive act exercising the sovereign power of a country (such as use of force against another country or a foreign individual) which cannot be challenged (or interfered with) by the courts. It includes any act of a government within its geographical boundaries which cannot be subject to the jurisdiction of the foreign courts.
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This definition come from http://www.businessdictionary.com/definition/act-of-state.html#ixzz1moJLjqAw. The Wiki gives a much more limited version.