Short answers, pulled from the story.
The city-state of Athens introduced the right of citizens to speak freely in the public assembly in the late 6th century BC. This era marked a shift where dissent was no longer met with exile or death but became a civic duty to criticize leaders and debate policy.
Pope Paul IV promulgated the Index Expurgatorius in 1559 as a catalog of prohibited books that grew to 300 editions. This document targeted thinkers like Galileo Galilei, Voltaire, and John Locke to control the output of printers and maintain the monopoly of the Roman Catholic Church over written thought.
John Milton published his masterpiece Areopagitica in 1644 as a direct response to the Parliament of England's reintroduction of government licensing of printers. The work argued that truth could only be discovered through the free encounter of ideas and that pre-censorship violated the divine mission of the English people.
John Stuart Mill published his treatise On Liberty in 1859 to articulate the most enduring justification for free speech. He argued that the only purpose for which power can be rightfully exercised over any member of a civilized community is to prevent harm to others.
The phrase I disapprove of what you say but I will defend to the death your right to say it was actually coined by biographer Evelyn Beatrice Hall in 1906. Although often attributed to Voltaire, the statement captures the essence of the Voltairean paradox regarding the defense of free speech for views one despises.
The Communications Decency Act of 1996 was partially overturned in the landmark case Reno v. ACLU in 1997. This legal battle marked the first major attempt by the United States Congress to regulate pornographic material on the Internet.