Allegations about the use of British airports to refuel CIA planes carrying terrorist suspects to countries where they are to be interrogated and tortured raise the question whether this has anything to do with us. Why should the UK be involved or concerned?
First, we are involved because of our obligations under international law. The UK is a party to the Convention against Torture which imposes an absolute prohibition on torture, with no exceptions. So is the US. The ban on torture applies not just to the act itself but also prohibits sending people to countries where there are substantial grounds for believing that they would be in danger of being tortured.
General rules of international law describe ways in which a state may be responsible for the acts of another: a state which assists another in committing a breach of international law is itself breaking the law if it does so in knowledge of the facts.
There would be serious concerns about the UK's own responsibility under the Torture Convention if the detainees are, as alleged, being flown to a country where they can be interrogated by methods amounting to torture, and if it were to be known by our Government that our airports were being used to assist with the flights.
Second, the allegations raise concerns under our own criminal law. The obligation under the Torture Convention has been translated into our law in the Criminal Justice Act 1988, an Act well known from its use in the Pinochet case. The Act creates the offence of torture and allows the courts to try it wherever the offence was committed and by a person of whatever nationality. Even if the persons concerned never leave a plane on the Tarmac at a British airport they are covered by the law.
The letters written on Tuesday by Liberty to various police constables claim that it amounts to torture to detain someone who is aware that the purpose of the detention is to bring them to a place where they will be subjected to torture, as that itself will undoubtedly inflict severe mental suffering. That is not an entirely fanciful claim. The Torture Convention requires states to begin an investigation wherever there is "reasonable ground" to believe that an act of torture has been committed in its territory.
Third, we must be concerned about these allegations because the relevant rules of international and domestic law reflect fundamental values of our society. No statement that "the rules of the game have changed" can apply to principles such as these. The Government's condemnation of torture needs to come across clearly in all areas of its domestic and foreign policy. The policy of seeking diplomatic assurances that persons deported from this country will not be tortured, controversial as it is, should be matched by a determination to avoid any form of assistance with the outsourcing of torture by others.
It has to be asked whether there is anything that could have been done by the Government in relation to the alleged flights; should the Government have known about any detainees on board and could these flights have been stopped?
The rules are different for civilian and state aircraft. In principle, civilian aircraft operating for non-commercial purposes are entitled to enter a state's airspace and land in its territory for reasons such as refuelling.
But are these civilian aircraft? If the allegations are correct, they are in use for reasons of the state, which would make them "state aircraft" for the purposes of international law. Governments can and do require permission before state aircraft land in their territory, and they are entitled to impose conditions for landing.
There is a need for the facts to come out. Reports about "extraordinary renditions" of persons to prisons abroad for coercive interrogation techniques are not new. The allegations about the use of British and other European airports have similarly been current for some months. If there is no truth in some of these claims, that should be said at once.
Elizabeth Wilmshurst is a former deputy head of the Foreign Office legal team and is now a fellow of Chatham House