In his post below, my co-blogger David Kopel considers some barriers to criminal prosecutions for torture of detainees during the Bush Administration. It's sort of hard to get into the details of the legal issues here because no one has been charged; the merits would depend on who was charged and for what. With that said, I did want to offer a few tentative thoughts about these issues.

  First, I think the important legal barrier to prosecution that David does not mention is the "entrapment by estoppel" defense, permitting reasonable reliance on an official statement of law -- here, the OLC opinions. How this would apply isn't entirely clear to me, as it would get into some difficult questions of what it means to reasonably rely on memos that assumed a set of facts that may have been inaccurate (such as the effect of the different interrogation methods, assumptions that were a big part of the reasoning of the memos). But that would also presumably depend on the individual prosecuted: Reasonable reliance is very fact-specific, and we would need to know exactly what the defendant knew about what OLC had said.

  The availability of an entrapment by estoppel defense would then raise all sorts of questions about classified information. Say a defendant is indicted, and his defense is that the details of the briefing he received on what he could do specifically allowed what he did. The court would need to get into questions of what information can be disclosed about this under the Classified Information Procedures Act, raising serious tensions between the due process rights of the defendant and the need to keep classified information secret.

  David raises the necessity defense as a possible defense. He writes:

My tentative view (not based on extensive research) is that Self-Defense and Necessity are inherent in our Anglo-American legal tradition of liberty, and that any statute which purports to exclude Self-Defense or Necessity should be unconstitutional.

  Self-defense wouldn't realistically be raised in a case of interrogation, at least barring very strange circumstances, so I think the real issue here is necessity. It turns out that the Supreme Court has not recognized a general necessity defense in federal criminal law, and the caselaw on whether and when it exists is pretty mixed. See generally Steven S. Schwartz, Note, Is There a Common Law Necessity Defense in Federal Criminal Law?, 75 U. Chi. L. Rev. 1259 (2008).

  I agree that the Supreme Court would likely recognize such a defense in the case of criminal charges for torture. At the same time, it's worth noting that the necessity defense (to the extent it exists in federal law) is actually quite narrow: It generally requires an imminent threat and no reasonable legal alternatives. See, e.g., United States v. White, 552 F.3d 240, 247 (2d. Cir. 2009). It wouldn't be enough for a defendant to say that he thought there was a risk of an eventual attack and that the enhanced interrogation techniques were on the whole a good idea.

  Finally, David mentions the Rule of Lenity and the case of Ireland v. United Kingdom. I tend to doubt either would play much of a role. The Rule of Lenity exists, but it is very in narrow in practice, Some observers would say it exists in theory but not in fact. And I'm not sure how Ireland v. United Kingdom is relevant: it is not an interpretation of U.S. law, as I understand it, and in any event it covers only some of the techniques authorized by DOJ in its memos.

  Anyway, I suspect all of this is academic. I don't expect the Obama Administration to charge anyone. And I should stress that my take on the legal issues here are tentative: I usually focus a lot more on surveillance issues than interrogation issues, so I haven't focused on the legal issues here as closely as some others. Still, I did want to offer a somewhat different take on some of the legal issues.