You cannot yell "FIRE" in a public theater, but in 1977, neo-Nazis could march in Skokie, Ill., a predominantly Jewish town. Today, in France, the French prosecutor asked Twitter to turn over the "data necessary for identifying the authors of anti-Semitic tweets that were accompanied by the hashtag #UnBonJuif (#AGoodJew.)," according to this article in Tech President and this one from NPR.
Did Twitter "cave" to French authorities? Do the authors of the anti-Semitic tweets have a right to freedom of speech? "The real issue," according to one observer, "is, technically, how can you tell the difference between real racists and fascists, and those simply talking or joking about the racist tweets?"
Here's a clip from NPR about the conflict.