Defamation is extremely hard to prove in the US, though some of Steyn’s antics, such as sacking his legal counsel definitely won’t help him.
On one hand, I’m in favour of the unfettered free speech which is possible in the US, without having to worry about censorship’s great disguise: hate speech.
On the other hand, climate change denialists are frankly more odious than the anti-vaccination movement in terms of harm they’ve caused (they’re also screwing up future generations).
I hope Mann doesn’t settle out of court and goes the whole way with this.