The Supreme Court ruled that an American citizen detained as an enemy combatant has the right to challenge the factual basis of their detention before a neutral decision-maker. Hamdi's father filed a writ of habeas corpus, alleging that his son's detention violated the Fifth and Fourteenth Amendments. The Fourth Circuit ruled that Hamdi's detention did not require a factual inquiry or evidentiary hearing as he was captured in an active combat zone. The court held that the President's detention of Hamdi was constitutional under his war powers, based on the factual averments in the Mobbs Declaration. The court confirmed that the AUMF authorizes the detention of individuals classified as "enemy combatants" for the duration of the relevant conflict, based on longstanding law-of-war principles. The court also held that indefinite detention for the purpose of interrogation is not authorized under the AUMF. The writ of habeas corpus and the Due Process Clause inform the procedural requirements for judicial review in this case. The definition of enemy combatant accepted by the court requires that Hamdi be "part of or supporting forces hostile to the United States or coalition partners" and "engaged in an armed conflict against the United States" to justify his detention.

The case involves Yaser Hamdi, an American citizen who was designated as an "enemy combatant" and denied access to counsel for almost two years. Hamdi's petition for writ of habeas corpus argues that he has not been charged with any crime under domestic law. The Government argues that Hamdi's detention as an enemy combatant falls within the President's power as Commander in Chief under the laws and usages of war, and is authorized by two statutes. The lower court may have erred in accepting the Government's position. The main issue is how to interpret the Non-Detention Act, which requires clear congressional authorization before any citizen can be detained. Congress intended to limit the Executive's power to detain citizens in wartime to protect national security. § 4001(a) was intended to prohibit not only the exercise of power to vindicate the interests underlying domestic criminal law but also to statutorily unauthorized detention by the Executive for reasons of security in wartime.

The case of Yaser Hamdi, an American citizen detained without charge as an enemy combatant, raises the issue of balancing national security and personal liberty. The dissenting opinion argues that military exigency is not enough to justify detention without charge, and the Constitution's Suspension Clause does not allow for it. The Due Process Clause requires the government to follow common-law procedures before depriving a person of life, liberty, or property. The writ of habeas corpus is explicitly mentioned in the Constitution and is considered a means to protect against arbitrary imprisonments. The Supreme Court has ruled that Hamdi is entitled to a habeas decree requiring his release unless criminal proceedings are promptly brought or Congress has suspended the writ of habeas corpus. The Suspension Clause is meant to ensure that citizens are either released or granted a fair trial, except in extreme cases when the writ can be suspended.

The Supreme Court ruled that executive decisions on foreign policy are political and not subject to judicial review. The Court recognized the primacy of the political branches in the foreign-affairs and national-security contexts. The burden of proof falls on those who challenge the President's actions, and the Court can only set aside the order if it conflicts with the Constitution or Congress's laws. The dissenting view argues that the President has the authority to detain enemy combatants in the war on terrorism, which is authorized by Congress through the AUMF. Judicial review of the Executive's decision to detain such individuals is not necessary and would undermine the Founders' belief in the importance of unity, secrecy, and dispatch in the warmaking function.