As a result of subsequent military action, particularly in Afghanistan, the United States captured numerous persons whom it suspected of ties to Al Qaeda or the Taliban—groups alleged to have perpetrated the 9/11 attacks or to have aided the perpetrators. Naval Station at Guantanamo Bay, Cuba. What legal frameworks limit the Executive's authority to detain and try persons captured in a military conflict as it sees fit? In what circumstances may Congress limit the federal courts' jurisdiction over petitions for habeas corpus? Justice Stevens has been a key player in the Supreme Court's resolution of such questions. He authored majority opinions in two significant cases, Rasul v. Bush and Hamdan v. Rumsfeld . This view of the habeas writ's historical role appeared to inform Justice Stevens's approach in post-9/11 cases. The dissenting opinion articulated the most restrictive view of executive power among the various opinions. Rasul v. Bush

After 9/11, numerous Guantanamo detainees submitted habeas petitions in federal courts to challenge their detentions. In several cases predating the habeas statute, the Court upheld federal courts' jurisdiction over writs of habeas corpus challenging wartime detentions. He challenged the planned military commission proceeding, arguing that (1) the Executive lacked the authority under existing statutes and the laws of war to use a military commission as the forum for a trial for the crime of conspiracy; and (2) the military commission procedures violated both the Uniform Code of Military Justice (i.e., Chapter 47 of Title 10 of the U.S. Code) and the Geneva Convention, under which he was entitled to be treated as a prisoner of war. Justices Scalia, Thomas, and Alito wrote dissenting opinions.
Justice John Paul Stevens played a pivotal role in determining the scope of executive-branch power in a post-9/11 world. After 9/11, Congress quickly authorized the Executive to respond to the terrorist attacks using military force. Difficult legal questions emerged from the consequences of the ensuing military actions, particularly as suspected members of Al Qaeda and the Taliban were captured in Afghanistan and elsewhere and transferred to the U.S. Naval Station at Guantanamo Bay, Cuba. Key questions included: What legal authorities restrict the Executive's ability to detain and try such persons as it sees fit? To what extent do detainees outside of the United States have the right to challenge their detentions in federal courts? When may Congress remove federal courts' jurisdiction over habeas cases?
Justice Stevens authored majority opinions in two leading cases, Rasul v. Bush and Hamdan v. Rumsfeld, in which the Court allowed detainees' habeas petitions to proceed and invalidated the early incarnation of military commissions, thereby rejecting the broader views of executive power articulated shortly after the 9/11 attacks. In the cases, his view prevailed over strongly articulated dissenting opinions authored by Justice Scalia and other justices.
For a more in-depth examination of the Supreme Court's post-9/11 decisions regarding habeas corpus, see CRS Report RL33180, Enemy Combatant Detainees: Habeas Corpus Challenges in Federal Court, by [author name scrubbed] and [author name scrubbed].