Christian Legal Society v. Martinez (2010) allowed restrictions on student groups’ right to exclude members — but it reaffirmed their rights “to express any viewpoint they wish — including a discriminatory one.”
That expression in quotes, as Eugene Volokh notes in his Washington Post article, comes from a Justice Oliver Wendell Holmes dissent in a 1929 Supreme Court opinion, but I think immediately of a far older quote:
I disapprove of what you say, but I will defend to the death your right to say it.
Which I always thought was Voltaire, but when I picked up Bartlett’s for confirmation, I learned that, no. The above much-quoted quote was only attributed to Voltaire. But a further footnote brought me this, from “a line in a letter [Voltaire wrote] to M. le Riche (February 6, 1770)”:
Monsieur l’abbé, I detest what you write, but I would give my life to make it possible for you to continue to write.
That’s not bad either.