British comedian John Oliver has a good defense in a defamation suit filed against him and HBO, the cable network that produces “Last Week Tonight with John Oliver,” said First Amendment veteran Floyd Abrams.

But if Oliver succeeds, he will do so not with his humor—which recently included a squirrel-costumed staff member—but because of his politics, Abrams said.

This week, a group of coal mining companies, led by Robert Murray, the CEO of Murray Energy Corp., filed suit against Oliver and HBO after “Last Week” aired a segment about the Trump administration's coal industry policies.