In First Amendment law, prior restraint is government action that prohibits speech or other expression before the speech happens.
Prior restraint typically happens in a few ways. It may be a statute or regulation that requires a speaker to acquire a permit or license before speaking. Prior restraint can also be a judicial injunction that prohibits certain speech. There is a third way--discussed below--in which the government outright prohibits a certain type of speech. Courts typically disfavor prior restraint and often find it to be unconstitutional.
Prior Restraint of Freedom of Press
The issue of prior restraint often occurred when the state sought to prevent a news publication from publishing something.
Near v Minnesota
In Near v. Minnesota, 283 U.S. 697 (1931), a statute authorized the prior restraint of a news publication. The Supreme Court held that such a statute is unconstitutional. However, the Court did find that prior restraint may be allowed in exceptional cases, such as when the nation is at war, or when the speech would incite violence.
New York Times v. U.S.
In New York Times v. U.S., 403 U.S. 713 (1971), the United States government tried to stop the New York Times and the Washington Post from publishing classified government documents. The Supreme Court held that the government's urging of "security" did not trump the newspapers' freedom of press as guaranteed by the First Amendment. The Court held that in order to support an issuance of prior restraint, the government needs to prove that the newspaper publication would cause inevitable, direct, and immediate danger to the United States.
Hazelwood School District v. Kuhlmeier
In Hazelwood School District v. Kuhlmeier, 484 U.S. 260 (1988), public school officials attempted to prevent the school's student-run newspaper from publishing certain information. The Supreme Court held that in a public school, educators are entitled to a higher degree of control over a student-run newspaper than a government would have over a professional newspaper.