Final answer:
Prior restraint is a governmental action that prevents speech or publication before it occurs. The Supreme Court has ruled against prior restraint in landmark cases including Near v. Minnesota and the Pentagon Papers case, highlighting that it is rarely justified and only permissible under exceptional circumstances.
Step-by-step explanation:
The concept of prior restraint refers to government actions that prevent speech or expression before it takes place. For example, forbidding the publication of a book that someone plans to release. The Supreme Court has set a high bar for when prior restraint can be justified, affirming that such actions carry the 'heaviest burden in constitutional law' and equating prior restraint to 'freezing' speech.
In the landmark case, Near v. Minnesota, the Court struck down a state law that allowed prior restraint as unconstitutional. Furthermore, in the Pentagon Papers case, the Supreme Court ruled that the government could not stop the New York Times and Washington Post from publishing materials from a secret history of the Vietnam War (the Pentagon Papers), reinforcing the principle that prior restraint is seldom permissible.
One of the most notable Supreme Court rulings on prior restraint came during the Pentagon Papers case, where the government's attempt to impose prior restraint on the publication of classified documents was overwhelmingly denied, citing a need for a very compelling reason to justify such an action.