This Wikipedia page is a nice jumping off place for the topic.
A very nice/quick video to set a base for the topic. Free Speech defined and historically explained.
A longer crash course. A nice documentary that cover a ton of ground
A Great discussion starter on the issue of free speech.
Micro- Aggression (8:00 mn)
A Great discussion starter on an issue of free speech.
Does Free Speech Offend You? (5:20)
Should offensive speech be banned? Where should we, as a society, draw the line where permitted speech is on one side, and forbidden speech is on the other? Should we even have that line? And should free speech be limited by things like trigger warnings and punishments for microaggressions? Greg Lukianoff, president of the Foundation for Individual Rights in Education, answers these questions and more.