Inter arma enim silent leg?s is a Latin phrase meaning "for among [times of] arms, the laws fall mute," but it is more popularly rendered as "in times of war, the law falls silent."
At the time that Cicero used the phrase, mob violence was common. Armed gangs led by partisan leaders controlled the streets of Rome; nevertheless such leaders were elected to high offices.
Abraham Lincoln's request for an opinion on the suspension of the right to habeas corpus during the American Civil War resulted eventually in the following decision, in Ex parte Merryman (1861), of Chief Justice Roger B. Taney, as a judge of the United States circuit court for the District of Maryland:
The United States' government explicitly referred to this maxim within its argument in the case Ex parte Milligan, when it remarked (with an additional reference to Cicero) 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.
The erosion of citizens' rights during World War II were upheld in the 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 on the same day.
In its more modern usage, the phrase has become a watchword about the erosion of civil liberties during wartime. In the immediate wake of the September 11 attacks, the maxim was aired and questioned in the media of the United States, with renewed force. The implication of the saying, as currently used, is in debate whether civil liberties and freedoms are 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," he wrote. "The laws will thus not be silent in time of war, but they will speak with a somewhat different voice."
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 US 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.