"Philippe Sands and Dahlia Lithwick have kindly responded to my post about CAT [Convention Against Torture] and the prosecution of torture suspects [in which Prof. Heller points out that the CAT may *require* signatory countries to prosecute those who torture].  Here is their response:

We don't believe we are in disagreement on the approach to the obligation under CAT, under Articles 7(1) and (2). The obligation is to "submit the case to its competent authorities for the purpose of prosecution". What happens thereafter is a matter for the prosecutor, who may decide that, in accordance with applicable standards ("authorities shall take their decision in the same manner as in the case of any ordinary offence of a serious nature under the law of that State") and the facts of the case, including the prospects for a successful prosecution, that proceeding to actual prosecution is not justified.

Weeks of hearings on Pinochet in the House of Lords and other English courts, in which Arts 5 and 7 were parsed to death, confirm that this is the proper approach to Article 7.

What does this mean for the US right now? In the face of rather compelling evidence that torture occurred -- not least the statement last week by Susan Crawford -- it appears that the matter should be taken up by a prosecutor..."

In the US, we have something called "prosecutorial discretion."  It means that the DA, or US Atty, or whatever gov't lawyer, doesn't have to prosecute anyone.  They are free to cut plea bargains or just let a case slide if they don't like the evidence.  From time to time, the decision to not prosecute has to do with politics.  And, under our laws, there's nothing wrong with that (unless the lawyer himself is mixed up in the same criminal activity, of course).  I think congressional republicans are trying to beat up Obama's Atty General choice in confirmation just to make sure that kind of thing happens--he'll be afraid to risk the political capital.

*(Prof. Heller is a law professor at the University of Aukland in New Zealand and a regular contributor to OpinioJuris.org)