First Amendment to the US Constitution.

The First Amendment (Amendment I) to the United States Constitution prevents Congress from making any law respecting an establishment of religion, prohibiting the free exercise of religion, or abridging the freedom of speech, the freedom of the press, the right to peaceably assemble, or to petition for a governmental redress of grievances. It was adopted on December 15, 1791, as one of the ten amendments that constitute the Bill of Rights.

The Bill of Rights was originally proposed to assuage Anti-Federalist opposition to Constitutional ratification. Initially, the First Amendment applied only to laws enacted by the Congress, and many of its provisions were interpreted more narrowly than they are today. Beginning with Gitlow v. New York (1925), the Supreme Court applied the First Amendment to states—a process known as incorporation—through the Due Process Clause of the Fourteenth Amendment.

In Everson v. Board of Education (1947), the Court drew on Thomas Jefferson's correspondence to call for "a wall of separation between church and State", though the precise boundary of this separation remains in dispute. Speech rights were expanded significantly in a series of 20th and 21st-century court decisions which protected various forms of political speech, anonymous speech, campaign financing, pornography, and school speech; these rulings also defined a series of exceptions to First Amendment protections. The Supreme Court overturned English common law precedent to increase the burden of proof for defamation and libel suits, most notably in New York Times Co. v. Sullivan (1964). Commercial speech, however, is less protected by the First Amendment than political speech, and is therefore subject to greater regulation.

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