I agree absolutely with Mark’s response to Sam below (except that I think Bollinger’s introduction was spoilt by pointless discourtesy and the hysterical and flattering error of describing Ahmedinejad as a “dictator”).
Sam may not like universal jurisdiction on war crimes, but it’s a growing legal fact in most of the civilised world. Pirates early achieved status in international law as common “enemies of humanity” and from Cicero onwards the general idea was that anybody had the right and duty to string them up (Cicero isn’t strong on due process, but Grotius thought promises to pirates should be kept as made before God). Applying the doctrine to war crimes and crimes against humanity is just a revival. The British House of Lords judgements allowing the extradition to Spain of Augusto Pinochet were based on it: though the majority reasoning differs between round 1 and round 2. Either way, even Bush could not rely in Britain on immunity as a former head of state.
Regardless of formal jurisdiction, prosecutors are less likely to investigate and courts to extradite in cases where there’s no national connection. Garzón’s arrest warrant for Pinochet was based partly on torture committed against many Chileans, but also against a smaller number of Spanish citizens. The global reach of the American GWOT has caught up the citizens of many countries in unlawful detention and abuse; most from doubtfully democratic states, but some from say Britain and Germany. Even restricting jurisdiction to cases involving or including nationals (on the Garzón model), the global legal web would still be extensive.
Universal jurisdiction is contentious, complicated and therefore uncertain in operation. The US opposes it along with (according to Wikipedia) such bastions of human rights as China and Russia. Even in its current inchoate state, universal jurisdiction can still serve as a serious warning to perpetrators and an incitement to countries to clean their own houses.
There is as it happens an excellent solution to these uncertainties: ratifying the statute of the International Criminal Court. Or the pirate can always cry “state sovereignty!” as he walks the plank.