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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.[1][2][3][4] The term "freedom of speech" embedded in the First Amendment encompasses the decision what to say as well as what not to say.[5] 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,[6] prevents only government restrictions on speech, not restrictions imposed by private individuals or businesses unless they are acting on behalf of the government.[7] 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.[8]

The First Amendment's freedom of speech right not only proscribes most government restrictions on the content of speech and ability to speak, but also protects the right to receive information,[9] prohibits most government restrictions or burdens that discriminate between speakers,[10] restricts the tort liability of individuals for certain speech,[11] and prevents the government from requiring individuals and corporations to speak or finance certain types of speech with which they do not agree.[12][13][14]

Categories of speech that are given lesser or no protection by the First Amendment include obscenity (as determined by the Miller test), fraud, child pornography, speech integral to illegal conduct,[15] speech that incites imminent lawless action, and regulation of commercial speech such as advertising.[16][17] Within these limited areas, other limitations on free speech balance rights to free speech and other rights, such as rights for authors over their works (copyright), protection from imminent or potential violence against particular persons, restrictions on the use of untruths to harm others (slander and libel), and communications while a person is in prison. When a speech restriction is challenged in court, it is presumed invalid and the government bears the burden of convincing the court that the restriction is constitutional.[18]