The prolonged indefinite detention without trial of terrorism suspects at Guantanamo Bay violates US obligations under international law. The Bush administration claimed unfettered power to detain persons on the basis of the president's role as commander-in-chief, which the Supreme Court rejected in 2008 in Boumediene v. Bush. The Obama administration has sought to justify indefinite detention without trial under authority of the Authorization for Use of Military Force (AUMF), enacted in 2001, which permits the president to use all necessary and appropriate force against al Qaeda and other organizations and individuals involved in the 9/11 attacks. The administration has also stated that its detention policies are "informed by principles of the laws of war."
The laws of war provide for the detention of prisoners-of-war and civilians who pose an imperative security risk during international armed conflicts - that is, conflicts between states. Guantanamo detainees apprehended during the international armed conflict in Afghanistan that began in 2001 should have been treated in accordance with the Geneva Conventions of 1949 and repatriated to Afghanistan after the Karzai government was created in 2002, ending the inter-state conflict, or prosecuted for war crimes. Also applicable during international armed conflicts is international human rights law, but the laws of war may take precedence as the more specific law (lex specialis).
During non-international armed conflicts, such as the current civil war in Afghanistan or other fighting between states and non-state armed groups, persons who take up arms or are otherwise involved in rebel activity may be detained and prosecuted in accordance with domestic laws. Such individuals are entitled to due process rights provided by international human rights law, which allows for some reductions in protections during declared public emergencies.
Although the Obama administration has abandoned the phrase "global war on terror," it continues to assert the authority to pick up and detain anyone anywhere in the world in accordance with the laws of war. However, individuals apprehended in situations not amounting to armed conflict, that is, outside a traditional battlefield, do not fall within the realm of the laws of war. They instead must be detained and prosecuted according to domestic law and international human rights law.
International human rights law, notably the International Covenant on Civil and Political Rights, which the US ratified in 1992, prohibits arbitrary detention. According to the United Nations Human Rights Committee, the international expert body that monitors compliance with the covenant, detentions are arbitrary if not in accordance with due process of law or are manifestly disproportional, unjust or unpredictable. Detention should be consistent with the normal procedures used to prosecute individuals implicated in criminal offenses, including terrorism charges. Detainees should be charged with recognized criminal offenses and speedily brought to a fair trial. Instead, US practice has been to empower authorities to detain people indefinitely, without the need to sustain evidence in court or to prove criminal responsibility.
Although current Guantanamo detainees have after many years been able to seek habeas corpus relief, their prolonged indefinite detention without due process protections circumvented arbitrarily the legal process and denied them the right to a trial without undue delay. Remaining Guantanamo detainees should be prosecuted in accordance with international fair trial standards, or safely repatriated to their home country or resettled in a third country.