Freedom of speech, or simply free speech, is a principle that supports the freedom of an individual to articulate opinions and ideas without fear of retaliation, censorship, or sanction. The term freedom of expression is typically used as a synonym, to include any act of seeking, receiving and imparting information or ideas, regardless of the medium used; thus artistic expression is usually included under this heading.

In the Western world, freedom of speech is perhaps most famously enshrined in law and most closely associated with two texts: the First Amendment to the United States Constitution and Article 19 of the Universal Declaration of Human Rights. The First Amendment places free speech among what have been called the "five freedoms," of religion, speech, press, assembly, and petition, and specifies that legislative authority (of the U.S. Congress) over free speech is limited: "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances." The Universal Declaration of Human Rights asserts the right asserts that free speech should not be interfered with, regardless of media or frontiers: "Everyone has the right to freedom of opinion and expression; this right includes freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers."

The U.N. asserted a more limited freedom of expression in itsInternational Covenant on Civil and Political Rights (ICCPR). This version of Article 19 states that the exercise of free speech rights carries "special duties and responsibilities" and may "therefore be subject to certain restrictions" when necessary "[f]or respect of the rights or reputation of others" or "[f]or the protection of national security or of public order (order public), or of public health or morals".

There are certain restrictions on speech that are not traditionally, in Anglo-American law, regarded being in conflict with freedom of speech; but, insofar as these are restrictions on speech, the freedom of speech is almost never regarded as entirely absolute.

Common legal exceptions to freedom of speech in the Anglo-American tradition include:

There are other categories of speech restrictions, or of forced speech, which are sometimes regarded as being in direct conflict with a right to free speech—but these are matters of considerable debate, either historically or recently, in different countries:

A common observation of free speech absolutists is that certain exceptions to free speech rights would be tantamount to violating free speech.

In any event, an important and deeply controversial philosophical question is: What exceptions should be regarded as violating the right to freedom of speech? If there is such a right, it must be possible for governments (and, traditionally, some other authorities such as organized religion) to violate it somehow.

Justifications for exceptions include the harm principle, proposed by John Stuart Mill in On Liberty , which suggests that: "the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others." The idea of the "offense principle" is also used in the justification of speech limitations, describing the restriction on forms of expression deemed offensive to society, considering factors such as extent, duration, motives of the speaker, and ease with which it could be avoided. With the evolution of the digital age, application of the freedom of speech becomes more controversial as new means of communication and restrictions arise, for example the Golden Shield Project, an initiative by Chinese government's Ministry of Public Security that filters potentially unfavorable data from foreign countries.

The right to freedom of expression has been interpreted to include the right to take and publish photographs of strangers in public areas without their permission or knowledge.

Freedom of speech and expression has a long history that predates modern international human rights instruments. It is thought that ancient Athens' democratic ideology of free speech may have emerged in the late 6th or early 5th century BC. The values of the Roman Republic included freedom of speech and freedom of religion.

Concepts of freedom of speech can be found in early human rights documents.

England's Bill of Rights 1689 legally established the constitutional right of 'freedom of speech in Parliament' which is still in effect. The Declaration of the Rights of Man and of the Citizen, adopted during the French Revolution in 1789, specifically affirmed freedom of speech as an inalienable right. The Declaration provides for freedom of expression in Article 11, which states that:

Article 19 of the Universal Declaration of Human Rights, adopted in 1948, states that:

Today, freedom of speech, or the freedom of expression, is recognized in international and regional human rights law. The right is enshrined in Article 19 of the International Covenant on Civil and Political Rights, Article 10 of the European Convention on Human Rights, Article 13 of the American Convention on Human Rights and Article 9 of the African Charter on Human and Peoples' Rights. Based on John Milton's arguments, freedom of speech is understood as a multi-faceted right that includes not only the right to express, or disseminate, information and ideas, but three further distinct aspects:

International, regional and national standards also recognize that freedom of speech, as the freedom of expression, includes any medium, be it orally, in written, in print, through the Internet or through art forms. This means that the protection of freedom of speech as a right includes not only the content, but also the means of expression.

The right to freedom of speech and expression is closely related to other rights, and may be limited when conflicting with other rights (see limitations on freedom of speech). The right to freedom of expression is also related to the right to a fair trial and court proceeding which may limit access to the search for information, or determine the opportunity and means in which freedom of expression is manifested within court proceedings. As a general principle freedom of expression may not limit the right to privacy, as well as the honor and reputation of others. However greater latitude is given when criticism of public figures is involved.

The right to freedom of expression is particularly important for media, which plays a special role as the bearer of the general right to freedom of expression for all. However, freedom of the press is not necessarily enabling freedom of speech. Judith Lichtenberg has outlined conditions in which freedom of the press may constrain freedom of speech, for example where the media suppresses information or stifles the diversity of voices inherent in freedom of speech. Lichtenberg argues that freedom of the press is simply a form of property right summed up by the principle "no money, no voice".

Freedom of speech is understood to be fundamental in a democracy.

The norms on limiting freedom of expression mean that public debate may not be completely suppressed even in times of emergency.

One of the most notable proponents of the link between freedom of speech and democracy is Alexander Meiklejohn. He argues that the concept of democracy is that of self-government by the people. For such a system to work an informed electorate is necessary. In order to be appropriately knowledgeable, there must be no constraints on the free flow of information and ideas. According to Meiklejohn, democracy will not be true to its essential ideal if those in power are able to manipulate the electorate by withholding information and stifling criticism. Meiklejohn acknowledges that the desire to manipulate opinion can stem from the motive of seeking to benefit society. However, he argues, choosing manipulation negates, in its means, the democratic ideal.

Eric Barendt has called this defense of free speech on the grounds of democracy "probably the most attractive and certainly the most fashionable free speech theory in modern Western democracies". Thomas I. Emerson expanded on this defense when he argued that freedom of speech helps to provide a balance between stability and change. Freedom of speech acts as a "safety valve" to let off steam when people might otherwise be bent on revolution. He argues that "The principle of open discussion is a method of achieving a more adaptable and at the same time more stable community, of maintaining the precarious balance between healthy cleavage and necessary consensus." Emerson furthermore maintains that "Opposition serves a vital social function in offsetting or ameliorating (the) normal process of bureaucratic decay."

Research undertaken by the Worldwide Governance Indicators project at the World Bank, indicates that freedom of speech, and the process of accountability that follows it, have a significant impact in the quality of governance of a country. "Voice and Accountability" within a country, defined as "the extent to which a country's citizens are able to participate in selecting their government, as well as freedom of expression, freedom of association, and free media" is one of the six dimensions of governance that the Worldwide Governance Indicators measure for more than 200 countries. Against this backdrop it is important that development agencies create grounds for effective support for a free press in developing countries.

Richard Moon has developed the argument that the value of freedom of speech and freedom of expression lies with social interactions.

Moon writes that "by communicating an individual forms relationships and associations with others – family, friends, co-workers, church congregation, and countrymen.

By entering into discussion with others an individual participates in the development of knowledge and in the direction of the community."

University campuses have historically been bastions of free speech.

UC Berkeley was the birthplace of the Free Speech Movement.

In recent times, many colleges and universities in the United States have retreated from historically strong support for free speech, including through the dis-invitation of speakers, promulgation of speech codes that prohibit what is deemed "offensive speech," and students protesting the participation of politically unpopular speakers on campus, including those widely regarded as outside the mainstream as well as those who are traditionalist Christians, pro-Israel, anti-abortion, or otherwise conservative.

This trend of activism by students and occasionally professors favoring the tightening of permissible speech was commented on and condemned by President Obama in 2015. Several high-profile incidents have occurred since 2014 in which large protests, which ranged in nature from peaceful disruption to widespread violence and rioting, periodically occurred on college campuses, such as at Yale University in 2016, at the University of Missouri in 2015, at the University of California Berkeley in 2017, at Middlebury College in 2017, at Evergreen State College in 2017, and elsewhere. The rise of far-left militant groups, such as Antifa, prompted in large part by the election of Donald Trump to the presidency, which are often attracted to college protests, have led to a rise in the level of violence of some protests.

University of California, Los Angeles Chancellor Gene Block issued a statement concerning both the value of free speech and the responsibility for civil discourse. The statement was in favor of an environment in which people coming from different beliefs and backgrounds may engage in passionate dialogue without belittling one another. In Block's view, "just because speech is constitutionally protected doesn’t mean that it is wise, fair or productive."

Legal systems sometimes recognize certain limits on the freedom of speech, particularly when freedom of speech conflicts with other rights and freedoms, such as in the cases of libel, slander, pornography, obscenity, fighting words, and intellectual property. Justifications for limitations to freedom of speech often reference the "harm principle" or the "offense principle". Limitations to freedom of speech may occur through legal sanction or social disapprobation, or both. Certain public institutions may also enact policies restricting the freedom of speech, for example speech codes at state schools.

In On Liberty (1859), John Stuart Mill argued that "...there ought to exist the fullest liberty of professing and discussing, as a matter of ethical conviction, any doctrine, however immoral it may be considered." Mill argues that the fullest liberty of expression is required to push arguments to their logical limits, rather than the limits of social embarrassment. However, Mill also introduced what is known as the harm principle, in placing the following limitation on free expression: "the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others."

In 1985, Joel Feinberg introduced what is known as the "offense principle", arguing that Mill's harm principle does not provide sufficient protection against the wrongful behaviors of others. Feinberg wrote "It is always a good reason in support of a proposed criminal prohibition that it would probably be an effective way of preventing serious offense (as opposed to injury or harm) to persons other than the actor, and that it is probably a necessary means to that end." Hence Feinberg argues that the harm principle sets the bar too high and that some forms of expression can be legitimately prohibited by law because they are very offensive. But, as offending someone is less serious than harming someone, the penalties imposed should be higher for causing harm. In contrast, Mill does not support legal penalties unless they are based on the harm principle. Because the degree to which people may take offense varies, or may be the result of unjustified prejudice, Feinberg suggests that a number of factors need to be taken into account when applying the offense principle, including: the extent, duration and social value of the speech, the ease with which it can be avoided, the motives of the speaker, the number of people offended, the intensity of the offense, and the general interest of the community at large.

Along similar lines as Mill, Jasper Doomen has argued that harm should be defined from the point of view of the individual citizen, not limiting harm to physical harm since nonphysical harm may also be involved; Feinberg's distinction between harm and offense is criticized as largely trivial.

In 1999, Bernard Harcourt wrote of the collapse of the harm principle: "Today the debate is characterized by a cacophony of competing harm arguments without any way to resolve them. There is no longer an argument within the structure of the debate to resolve the competing claims of harm. The original harm principle was never equipped determine the relative importance of harms."

Interpretations of both the harm and offense limitations to freedom of speech are culturally and politically relative.

For instance, in Russia, the harm and offense principles have been used to justify the Russian LGBT propaganda law restricting speech (and action) in relation to LGBT issues. A number of European countries that take pride in freedom of speech nevertheless outlaw speech that might be interpreted as Holocaust denial. These include Austria, Belgium, Czech Republic, France, Germany, Hungary, Israel, Liechtenstein, Lithuania, Luxembourg, Netherlands, Poland, Portugal, Slovakia, and Switzerland.

Kurt Westergaard, a Danish cartoonist, created the controversial cartoon of the Islamic prophet Muhammad wearing a bomb in his turban and was met with strong violent reactions worldwide.

Norman Finkelstein, a writer and professor of political science expressed the opinion that Charlie Hebdo' s abrasive cartoons of Muhammad exceeded the boundaries of free speech, and compared those cartoons with the cartoons of Julius Streicher, who was hanged by the Allies after World War II for the words and drawings he had published. In 2006, in response to a particularly abrasive issue of Charlie Hebdo, French President Jacques Chirac condemned "overt provocations" which could inflame passions. "Anything that can hurt the convictions of someone else, in particular religious convictions, should be avoided", Chirac said.

In the U.S., the standing landmark opinion on political speech is Brandenburg v. Ohio (1969), expressly overruling Whitney v. California. In Brandenburg, the US Supreme Court referred to the right even to speak openly of violent action and revolution in broad terms:

The opinion in Brandenburg discarded the previous test of "clear and present danger" and made the right to freedom of (political) speech's protections in the United States almost absolute. Hate speech is also protected by the First Amendment in the United States, as decided in R.A.V. v. City of St. Paul , (1992) in which the Supreme Court ruled that hate speech is permissible, except in the case of imminent violence. See the First Amendment to the United States Constitution for more detailed information on this decision and its historical background.

Jo Glanville, editor of the Index on Censorship , states that "the Internet has been a revolution for censorship as much as for free speech". International, national and regional standards recognise that freedom of speech, as one form of freedom of expression, applies to any medium, including the Internet. The Communications Decency Act (CDA) of 1996 was the first major attempt by the United States Congress to regulate pornographic material on the Internet. In 1997, in the landmark cyberlaw case of Reno v. ACLU , the US Supreme Court partially overturned the law. Judge Stewart R. Dalzell, one of the three federal judges who in June 1996 declared parts of the CDA unconstitutional, in his opinion stated the following:

The World Summit on the Information Society (WSIS) Declaration of Principles adopted in 2003 makes specific reference to the importance of the right to freedom of expression for the "Information Society" in stating:

According to Bernt Hugenholtz and Lucie Guibault the public domain is under pressure from the "commodification of information" as information with previously little or no economic value has acquired independent economic value in the information age. This includes factual data, personal data, genetic information and pure ideas. The commodification of information is taking place through intellectual property law, contract law, as well as broadcasting and telecommunications law.

Freedom of information is an extension of freedom of speech where the medium of expression is the Internet. Freedom of information may also refer to the right to privacy in the context of the Internet and information technology. As with the right to freedom of expression, the right to privacy is a recognised human right and freedom of information acts as an extension to this right. Freedom of information may also concern censorship in an information technology context, i.e. the ability to access Web content, without censorship or restrictions.

Freedom of information is also explicitly protected by acts such as the Freedom of Information and Protection of Privacy Act of Ontario, in Canada.

The concept of freedom of information has emerged in response to state sponsored censorship, monitoring and surveillance of the internet. Internet censorship includes the control or suppression of the publishing or accessing of information on the Internet. The Global Internet Freedom Consortium claims to remove blocks to the "free flow of information" for what they term "closed societies". According to the Reporters without Borders (RWB) "internet enemy list" the following states engage in pervasive internet censorship: China, Cuba, Iran, Myanmar / Burma, North Korea, Saudi Arabia, Syria, Turkmenistan, Uzbekistan, and Vietnam.

A widely publicized example of internet censorship is the "Great Firewall of China" (in reference both to its role as a network firewall and to the ancient Great Wall of China). The system blocks content by preventing IP addresses from being routed through and consists of standard firewall and proxy servers at the Internet gateways. The system also selectively engages in DNS poisoning when particular sites are requested. The government does not appear to be systematically examining Internet content, as this appears to be technically impractical. Internet censorship in the People's Republic of China is conducted under a wide variety of laws and administrative regulations, including more than sixty regulations directed at the Internet. Censorship systems are vigorously implemented by provincial branches of state-owned ISPs, business companies, and organizations.

Before the invention of the printing press a written work, once created, could only be physically multiplied by highly laborious and error-prone manual copying. No elaborate system of censorship and control over scribes existed, who until the 14th century were restricted to religious institutions, and their works rarely caused wider controversy. In response to the printing press, and the heresies it allowed to spread, the Roman Catholic Church moved to impose censorship. Printing allowed for multiple exact copies of a work, leading to a more rapid and widespread circulation of ideas and information (see print culture). The origins of copyright law in most European countries lie in efforts by the Roman Catholic Church and governments to regulate and control the output of printers.

In 1501 Pope Alexander VI issued a Bill against the unlicensed printing of books and in 1559 the Index Expurgatorius, or List of Prohibited Books, was issued for the first time. The Index Expurgatorius is the most famous and long lasting example of "bad books" catalogues issued by the Roman Catholic Church, which presumed to be in authority over private thoughts and opinions, and suppressed views that went against its doctrines. The Index Expurgatorius was administered by the Roman Inquisition, but enforced by local government authorities, and went through 300 editions. Amongst others, it banned or censored books written by René Descartes, Giordano Bruno, Galileo Galilei, David Hume, John Locke, Daniel Defoe, Jean-Jacques Rousseau and Voltaire. While governments and church encouraged printing in many ways because it allowed for the dissemination of Bibles and government information, works of dissent and criticism could also circulate rapidly. As a consequence, governments established controls over printers across Europe, requiring them to have official licenses to trade and produce books.

The notion that the expression of dissent or subversive views should be tolerated, not censured or punished by law, developed alongside the rise of printing and the press. Areopagitica , published in 1644, was John Milton's response to the Parliament of England's re-introduction of government licensing of printers, hence publishers. Church authorities had previously ensured that Milton's essay on the right to divorce was refused a license for publication. In Areopagitica, published without a license, Milton made an impassioned plea for freedom of expression and toleration of falsehood, stating:

Milton's defense of freedom of expression was grounded in a Protestant worldview and he thought that the English people had the mission to work out the truth of the Reformation, which would lead to the enlightenment of all people. But Milton also articulated the main strands of future discussions about freedom of expression. By defining the scope of freedom of expression and of "harmful" speech Milton argued against the principle of pre-censorship and in favor of tolerance for a wide range of views. Freedom of the press ceased being regulated in England in 1695 when the Licensing Order of 1643 was allowed to expire after the introduction of the Bill of Rights 1689 shortly after the Glorious Revolution. The emergence of publications like the Tatler (1709) and the Spectator

As the "menace" of printing spread, more governments attempted to centralize control.

The French crown repressed printing and the printer Etienne Dolet was burned at the stake in 1546. In 1557 the British Crown thought to stem the flow of seditious and heretical books by chartering the Stationers' Company. The right to print was limited to the members of that guild, and thirty years later the Star Chamber was chartered to curtail the "greate enormities and abuses" of "dyvers contentyous and disorderlye persons professinge the arte or mystere of pryntinge or selling of books." The right to print was restricted to two universities and to the 21 existing printers in the city of London, which had 53 printing presses. As the British crown took control of type founding in 1637 printers fled to the Netherlands. Confrontation with authority made printers radical and rebellious, with 800 authors, printers and book dealers being incarcerated in the Bastille in Paris before it was stormed in 1789.

A succession of English thinkers was at the forefront of early discussion on a right to freedom of expression, among them John Milton (1608–74) and John Locke (1632–1704). Locke established the individual as the unit of value and the bearer of rights to life, liberty, property and the pursuit of happiness. However Locke's ideas evolved primarily around the concept of the right to seek salvation for one's soul, and was thus primarily concerned with theological matters. Locke neither supported a universal toleration of peoples nor freedom of speech; according to his ideas, some groups, such as atheists, should not be allowed.

By the second half of the 17th century philosophers on the European continent like Baruch Spinoza and Pierre Bayle developed ideas encompassing a more universal aspect freedom of speech and toleration than the early English philosophers. By the 18th century the idea of freedom of speech was being discussed by thinkers all over the Western world, especially by French philosophes like Denis Diderot, Baron d'Holbach and Claude Adrien Helvétius. The idea began to be incorporated in political theory both in theory as well as practice; the first state edict in history proclaiming complete freedom of speech was the one issued December 4, 1770 in Denmark-Norway during the regency of Johann Friedrich Struensee. However Struensee himself imposed some minor limitations to this edict in October 7, 1771, and it was even further limited after the fall of Struensee with legislation introduced in 1773, although censorship was not reintroduced.

John Stuart Mill (1806–1873) argued that without human freedom there can be no progress in science, law or politics, which according to Mill required free discussion of opinion. Mill's On Liberty , published in 1859 became a classic defence of the right to freedom of expression. Mill argued that truth drives out falsity, therefore the free expression of ideas, true or false, should not be feared. Truth is not stable or fixed, but evolves with time. Mill argued that much of what we once considered true has turned out false. Therefore, views should not be prohibited for their apparent falsity. Mill also argued that free discussion is necessary to prevent the "deep slumber of a decided opinion". Discussion would drive the onwards march of truth and by considering false views the basis of true views could be re-affirmed. Furthermore, Mill argued that an opinion only carries intrinsic value to the owner of that opinion, thus silencing the expression of that opinion is an injustice to a basic human right. For Mill, the only instance in which speech can be justifiably suppressed is in order to prevent harm from a clear and direct threat. Neither economic or moral implications, nor the speakers own well-being would justify suppression of speech.

In Evelyn Beatrice Hall's biography of Voltaire, she coined the following sentence to illustrate Voltaire's beliefs: "I disapprove of what you say, but I will defend to the death your right to say it." Hall's quote is frequently cited to describe the principle of freedom of speech. In the 20th Century, Noam Chomsky states that: "If you believe in freedom of speech, you believe in freedom of speech for views you don't like. Stalin and Hitler, for example, were dictators in favor of freedom of speech for views they liked only. If you're in favor of freedom of speech, that means you're in favor of freedom of speech precisely for views you despise." Lee Bollinger argues that "the free speech principle involves a special act of carving out one area of social interaction for extraordinary self-restraint, the purpose of which is to develop and demonstrate a social capacity to control feelings evoked by a host of social encounters." Bollinger argues that tolerance is a desirable value, if not essential. However, critics argue that society should be concerned by those who directly deny or advocate, for example, genocide (see limitations above).