In the United States, freedom of speech and expression is strongly protected from government restrictions by the First Amendment to the U.S. Constitution, many state constitutions, and state and federal laws. Freedom of speech, also called free speech, means the free and public expression of opinions without censorship, interference and restraint by the government The term "freedom of speech" embedded in the First Amendment encompasses the decision what to say as well as what not to say. The Supreme Court of the United States has recognized several categories of speech that are given lesser or no protection by the First Amendment and has recognized that governments may enact reasonable time, place, or manner restrictions on speech. The First Amendment's constitutional right of free speech, which is applicable to state and local governments under the incorporation doctrine, prevents only government restrictions on speech, not restrictions imposed by private individuals or businesses unless they are acting on behalf of the government. However, It can be restricted by time, place and manner in limited circumstances. Some laws may restrict the ability of private businesses and individuals from restricting the speech of others, such as employment laws that restrict employers' ability to prevent employees from disclosing their salary to coworkers or attempting to organize a labor union.

The First Amendment to the United States Constitution prevents the government from making laws respecting an establishment of religion; prohibiting the free exercise of religion; or abridging the freedom of speech, the freedom of the press, the freedom of assembly, or the right to petition the government for redress of grievances. It was adopted on December 15, 1791, as one of the ten amendments that constitute the Bill of Rights.