He's a liar. Anyone remember John Demjanjuk, who was deported to Israel and charged with being the Nazi prison guard, "Ivan the Terrible"? Dershowitz went balistic when the guy claimed he wasn't Ivan the Terrible and continued to explode, when Pat Buchanan supported Demjanjuk's claim. Guess what? In the end, the Israeli supreme court cleared Demjanjuk.
If Dershowitz got that upset about a person, accused of being a Nazi, defending himself on the basis of mistaken identity, does anyone take seriously the claim that he would defend Hitler?
No, I take that back. Dershowitz would defend Hitler, if it gave him a chance to say nasty things about the U.S.