"The Convention Against Torture prohibits nations from expelling, returning or extraditing a person to another State "where there are substantial grounds for believing that he would be in danger of being subjected to torture." The U.S. has interpreted this to apply only where it is more likely than not that the person will be tortured -- i.e., the odds of torture must be over 50 percent.
Now, the Bush Administration claims it does not have to abide by this treaty obligation unless the person in question is in the United States proper. (More on this claim here.) Nevertheless, the Administration insists that as a matter of "policy" it will not render detainees to nations where it is more likely than not they will be tortured. This is how the State Department described that U.S. policy, in a Report to the United Nations on the Convention Against Torture:
The United States is aware of allegations that it has transferred individuals to third countries where they have been tortured. The United States does not transfer persons to countries where the United States believes it is "more likely than not" that they will be tortured. This policy applies to all components of the United States government.Despite this policy, the U.S. virtually never finds that someone is more likely than not to be tortured, even in nations with substantial, confirmed records of torture and abuse, such as Syria, Egypt, Iraq, Haiti, etc. We have sent persons, including detainees, to all of these places upon findings (often based on so-called "assurances") that the risk of torture was less than 50 percent."