The Guantanamo Bay detention camp (Spanish: Centro de detencin de la baha de Guantnamo) is a United States military prison located within Guantanamo Bay Naval Base, also referred to as Guantnamo, GTMO, and Gitmo (), on the coast of Guantnamo Bay in Cuba. Of the roughly 780 people detained there since January 2002 when the military prison first opened after the September 11 attacks, 733 have been transferred elsewhere, 36 remain there, and 9 have died while in custody.The camp was established by U.S. President George W. Bush's administration in 2002 during the War on Terror following the September 11, 2001 attacks. Indefinite detention without trial led the operations of this camp to be considered a major breach of human rights by Amnesty International, and a violation of the Due Process Clause of the Fifth and Fourteenth amendments of the United States Constitution by the Center for Constitutional Rights.Bush's successor, U.S. President Barack Obama, promised that he would close the camp, but met strong bipartisan opposition from the U.S. Congress, which passed laws to prohibit detainees from Guantanamo being imprisoned in the U.S. During President Obama's administration, the number of inmates was reduced from about 245 to 41.In January 2018, U.S. President Donald Trump signed an executive order to keep the detention camp open indefinitely. In May 2018, a prisoner was repatriated to Saudi Arabia during President Trump's administration. In early February 2021, the administration of U.S. President Joe Biden declared his intention to shut down the facility before he leaves office, though critics have noted that the Biden administration has taken few to no steps in the direction of closure. In July 2021, an additional detainee was released. In December 2021, The New York Times reported the Pentagon is building a second facility courtroom, in which the public will not be allowed to view the proceedings.

Hamdan v. Rumsfeld, 548 U.S. 557 (2006), is a case in which the Supreme Court of the United States held that military commissions set up by the Bush Administration to try detainees at Guantanamo Bay lack "the power to proceed because its structures and procedures violate both the Uniform Code of Military Justice and the four Geneva Conventions signed in 1949." Specifically, the ruling says that Common Article 3 of the Geneva Conventions was violated.

The case considers whether the United States Congress may pass legislation preventing the Supreme Court from hearing the case of an accused combatant before his military commission takes place, whether the special military commissions which had been set up violated federal law (including the Uniform Code of Military Justice and treaty obligations), and whether courts can enforce the articles of the Geneva Conventions.An unusual aspect of the case was an amicus brief filed by Senators Jon Kyl and Lindsey Graham, which presented an "extensive colloquy" added to the Congressional record as evidence that "Congress was aware" that the Detainee Treatment Act of 2005 would strip the Supreme Court of jurisdiction to hear cases brought by the Guantanamo detainees. Because these statements were not included in the December 21 debate at the time, Emily Bazelon of Slate magazine has argued that their brief was an attempt to mislead the court.On June 29, 2006, the Court issued a 5–3 decision holding that it had jurisdiction, and that the administration did not have authority to set up these particular military commissions without congressional authorization, because they did not comply with the Uniform Code of Military Justice and the Geneva Conventions (which the court found to be incorporated into the Uniform Code of Military Justice).