A suspension of the writ of habeas corpus empowers the President to indefinitely detain those suspected of endangering the public safety. In other words, it works a temporary suspension of civil liberties. Given the gravity of this power, the Suspension Clause narrowly limits the circumstances in which it may be exercised: the writ may be suspended only in cases of "rebellion or invasion" and when "the public Safety may require it. " Congress alone can suspend the writ; the Executive cannot declare himself authorized to detain in violation of civil rights. Despite the traditional emphasis on the importance of exclusive legislative authority over suspension, the statutes that Congress has enacted are in tension with it. Each of the suspension statutes has delegated broad authority to the President, permitting him in almost every case to decide whether, when, where, and for how long to exercise emergency power. Indeed, if all of these prior statutes are constitutional, Congress could today enact a law authorizing the President to suspend the writ in Guantanamo Bay if he decides at some point in the (perhaps distant) future that the constitutional prerequisites are satisfied. Such a broad delegation undermines the structural benefits that allocating the suspension decision to Congress is designed to achieve. This Article explores whether such delegations are constitutionally permissible. It concludes that while the Suspension Clause does not prohibit Congress from giving the President some responsibility for the suspension decision, it does require Congress to decide the most significant constitutional predicates for itself that an invasion or rebellion has occurred and that protecting the public safety may require the exercise of emergency power. Congress made this determination during the Civil War, but it violated the Suspension Clause in every other case by enacting a suspension statute before an invasion or rebellion actually occurred and in some instances, before one was even on the horizon.