Previous restraint, also known as prior restraint or censorship, refers to official governmental restrictions imposed on speech or other forms of expression before actual publication or dissemination. This type of regulation prevents the expression from occurring in the first place. Any system of prior restraint comes to court bearing a heavy presumption against its constitutional validity, and the government bears the heavy burden of showing justification for its enforcement.

Examples include closing newspaper offices or requiring permission before publication. It is generally only permissible under specific, strict conditions, such as demonstrating a clear and present danger of a substantive evil.