Guantánamo-the-prison on the US naval base on Guba was created to detain Muslim males captured in the "war on terror." Guantánamo is a sui generis phenomenon because its creation revealed a preexisting but unacknowledged weakness in the rule of law and its continued existence actively degrades the rule of law. In this paper, I argue that Guantánamo is a phenomenon with expanding international repercussions for the rule of law. Guantánamo is not like other US prisons that existed at the time of its creation because people imprisoned there were assigned a rightless status by presidential decree even before anyone was taken into US custody. Men and boys transferred to Guantánamo were held largely incommunicado and their identities were classified. Secret detention was a sui generis phenomenon for the United States, and Guantánamo was its address. While other regimes disappear and torture people, Guantánamo was constructed through legal interpretations, rationales, and justifications—it was made “legal” by government lawyers. In the “war on terror,” the CIA’s top-secret detention and interrogation program was a separate operation. But its secret program became part of the Guantánamo phenomenon when the Bush White House passed along the menu of torture techniques authorized for the CIA and the accompanying legal rationales to the Pentagon which adopted them for military interrogators at Guantánamo. The Guantánamo phenomenon throws into relief the meaning of “legal laws.” By 2001, there was a universal consensus—in principle, if not practice—that fighting wars legally required adherence to the 1949 Geneva Conventions. Guantánamo was created to undermine this consensus under the cover of “law.” This executive power grab, which has not been reversed, illuminates a preexisting but unacknowledged and previously unexploited weakness in the rule of law. The Guantánamo phenomenon includes the ways other governments emulated US “war on terror” prisoner policies. It also illustrates the manufactured inefficacy of international criminal law enforcement. The impunity of US officials was produced by the refusal of successive US administrations to punish criminal violations of international laws in domestic courts, and the willingness of courts to accept government arguments that such cases are non-justiciable. Impunity was transnationalized by US diplomatic pressure on foreign governments, either by securing their dismissal of cases against US officials in own courts or stonewalling the mandate of the ICC. The combined effects have done grave and possibly irreparable damage to the rule of law internationally.