The details of American antiterrorism policies, put in place after 9/11, are still largely hidden, but more pieces of this sordid history are dribbling out.

A valuable new report issued this month by the Open Society Justice Initiative documents the extent of the Central Intelligence Agency’s use of extraordinary rendition — the practice of abducting suspected terrorists and transferring them to countries with reputations for torturing prisoners during interrogations.

Reporting by The Times and other news media has long established that the C.I.A. operated a secret detention program with “black site” prisons outside the United States. In December, the Senate Intelligence Committee approved a highly critical, classified report on this program that has not been released. Committee members invoked its findings without revealing any useful new information at the recent confirmation hearing for John Brennan, the Obama administration’s top counterterrorism official, who was named to head the C.I.A. But the committee chairwoman, Senator Dianne Feinstein of California, has said that the black sites and coercive techniques were “terrible mistakes.”

According to the Open Society report, 54 countries participated in this program, including many where the rule of law is weak or nonexistent, like Afghanistan, Pakistan, Egypt, Malaysia and Somalia. More surprising and alarming is the collusion of leading democracies. Belgium, Finland and Denmark, among others, allowed their airports and airspace to be used for flights associated with C.I.A. rendition operations. Britain, Italy, Germany and Australia helped interrogate one or more suspects and either allowed or actively aided in their transfers.