In a world of sovereign states, gathering evidence is one of the major challenges for the new international criminal tribunals. The decision in Prosecutor v. Blaškić, by the Appeals Chamber of the International Criminal Tribunal for the former Yugoslavia, shows some of the difficulties. The Tribunal finds it has the power to issue compulsory orders to sovereign states for the production of evidence, although not to issue a subpoena as such. The Tribunal also assumes the power to review a state's national security privilege, a holding that may challenge the more protective provisions of the new Rome treaty for a permanent International Criminal Court. However, the Appeals Chamber's declaration that there is no power to summon particular government officials, even for eyewitness testimony, that document production must be limited, and that its orders cannot be directly enforced, may hobble the Tribunal's capacity to muster the necessary proof at trial.