Inter arma enim silent leges is a Latin phrase meaning "For among [times of] arms, the laws fall mute," although it is more popularly rendered as "In times of war, the law falls silent." This maxim was likely first written in these words by Cicero in his published oration Pro Milone, although Cicero's actual wording was "Silent enim leges inter arma." Given Cicero's in depth knowledge of Greek political history, It can be argued that his notion on war and law was inspired by Thucydides opinion on the violent nature of war and the realistic approach in international relations.
At the time when Cicero used this phrase, mob violence was common. Armed gangs led by thuggish partisan leaders controlled the streets of Rome. Such leaders were nevertheless elected to high offices.
In the United States, President Lincoln's request for an opinion on the suspension of a basic right, to habeas corpus, during the Civil War resulted eventually in the decision, in Ex parte Merryman (1861), of Chief Justice Roger Taney, sitting as a judge of the United States Circuit Court for the District of Maryland, that: "1. That the president [...] cannot suspend the privilege of the writ of habeas corpus, nor authorize a military officer to do it. 2. That a military officer has no right to arrest and detain a person not subject to the rules and articles of war [...] except in aid of the judicial authority, and subject to its control." The Supreme Court explicitly referred to this maxim within its ruling on the case Ex parte Milligan, when it remarked that "these [amendments of the Bill of Rights], in truth, are all peace provisions of the Constitution and, like all other conventional and legislative laws and enactments, are silent amidst arms, and when the safety of the people becomes the supreme law."
Erosion of citizens' rights during World War II were upheld in the United States Supreme Court case Hirabayashi v. United States (1943), which held that the application of curfews against members of a minority group were constitutional when the nation was at war with the country from which that group originated. Yasui v. United States was a companion case decided the same day.
In more modern usage, it has become a watchword about the erosion of civil liberties during wartime. In the immediate wake of the terrorist attacks of 11 September 2001, the maxim was aired and questioned in the American media with renewed force. The implication of the saying, as currently used, is in debate whether civil liberties and freedoms are in fact subservient to a wartime nation's duty of self-defense.
In 1998 Chief Justice William Rehnquist, in All the Laws but One: Civil Liberties in Wartime suggested that "the least justified of the curtailments of civil liberty" were unlikely to be accepted by the courts in wars of the future. "It is neither desirable nor is it remotely likely that civil liberty will occupy as favored a position in wartime as it does in peacetime. But it is both desirable and likely that more careful attention will be paid by the courts to the basis for the government's claims of necessity as a basis for curtailing civil liberty," the chief justice wrote. "The laws will thus not be silent in time of war, but they will speak with a somewhat different voice."
An episode of The Practice (6th season, episode 111, aired 9 December 2001) bearing the title "Inter Arma Silent Leges" examined this political concept in the context of the imprisonment of an Arab-American immigrant, three months after the terrorist attack of 9/11/2001.
In 2004, Justice Antonin Scalia used this phrase to decry the plurality decision in Hamdi v. Rumsfeld which in his view, upheld the detention of a U.S. citizen as an enemy combatant, without charge or suspension of the habeas corpus.
"Many think it not only inevitable but entirely proper that liberty give way to security in times of national crisis that, at the extremes of military exigency, inter arma silent leges. Whatever the general merits of the view that war silences law or modulates its voice, that view has no place in the interpretation and application of a Constitution designed precisely to confront war and, in a manner that accords with democratic principles, to accommodate it."