By Stephen Mulvey
Europe reporter, BBC News
If the allegations of secret CIA jails in Poland and Romania prove to be true, the results could be very serious for both countries.
EU Justice Commissioner Franco Frattini has suggested suspending the voting rights of any member state found to have broken the EU's founding principles of respect for human rights and the rule of law.
Mr Marty and MEPs have been ignored by European governments
A senior German MEP, Elmar Brok, meanwhile, suggested in January that Romania's EU membership should be delayed if it still had a CIA jail on its territory.
In practice, neither sanction would be easy to achieve.
The decision to suspend a country's voting rights would have to be agreed unanimously by all the other member states. And Romania's accession treaty has already been signed.
The damage would most likely be confined to the reputation of the two countries.
"If there was a... torture camp on Polish territory, my goodness, it would be the scandal of the century," former UK Europe Minister Denis MacShane told the BBC on Wednesday, expressing strong doubts that this was the case.
Jury still out
However, it's not only Poland and Romania that would end up in the dock of international public opinion, if Mr Marty's accusations are true.
For example, his report accuses seven countries of responsibility "at varying degrees, which are not always settled definitively" for violating the rights of named "rendered" individuals: Sweden, Bosnia, the UK, Italy, Macedonia, Germany and Turkey.
This is tantamount to an invitation for the individuals to put the countries in a real dock - by taking them to the European Court of Human Rights, if they fail to get redress through national courts.
But it's still not clear whether Mr Marty's report will come to be accepted as an accurate account of US renditions in Europe.
A resolution based on the report was approved by the legal affairs committee of the Parliamentary Assembly of the Council of Europe (PACE) on Wednesday.
It now faces a vote at a plenary session of the assembly on 27 June.
Mr MacShane, a British Labour MP and PACE member told the BBC World Service's Europe Today programme the report was made up of "fantasies".
He accused Dick Marty of "going round collecting newspaper clippings and producing extraordinary allegations against the Poles and Romanians, which frankly are not worth serious parliamentary discussion".
A report by a temporary committee of the European Parliament, which reaches similar conclusions, also has various hurdles to pass.
The committee votes on it on Monday, prior to a plenary session in July.
British Conservative MEP Charles Tannock, said centre-right members of the committee would be voting to reject the report, which he said was based on "a lot of hearsay, a lot of accusations, and very little proof".
"It's been an exercise in bashing America," he said.
A third report on the verge of publication comes from the Secretary-General of the Council of Europe, Terry Davis.
European governments have been able to spurn requests for information from Mr Marty and the European Parliament committee, but they have been obliged to answer Mr Davis' questions.
Nearly all appear to have denied any wrongdoing, but Mr Davis said in April: "On the basis of the information I have received so far, I am now in position to say that we no longer need to speak about 'alleged' cases of rendition."
His interim report in February said that renditions involved "multiple human rights violations".
But Mr Davis' goal is not to expose guilt, or to propose sanctions, so much as to prompt member states to change their laws, to prevent anything similar happening in Europe again.
"Under the European Convention of Human Rights, governments are not only obliged not to do these things, they are obliged to put in place legislation to make it impossible for these things to happen," says Mr Davis' spokesman, Matjaz Gruden.
According to Baroness Sarah Ludford, vice-chairman of the European Parliament's committee on CIA renditions, the best way to establish the truth or otherwise of the allegations is for governments themselves, or national parliaments, to hold official inquiries.
"I want the EU to say we cannot go on like this, we cannot dodge these allegations, we have to have proper formal investigations. We have to own up and clean house," she says.
And if the allegations are confirmed, it's the bigger countries such as the UK, Germany and Italy that will be most to blame she says, because they were in a stronger position to "assert vis-a-vis the US the primacy of respect for human rights".