Hours after the September 11, 2001, terrorist attacks, Ward Churchill compared the victims to the Nazis. A professor of ethnic studies at the University of Colorado at Boulder, he wrote in an essay that those killed in the World Trade Center were not innocent civilians but "little Eichmanns." The analogy is so outrageous, one thinks, that surely he immediately got into trouble. Surely it prompted angry letters and calls for him to be fired. But it didn't. Instead, for years the comparison just sat there quietly. Mr. Churchill, on the other hand, rarely stays still. He has spoken at more...