Kevin Drum and Glenn Greenwald both say it's time to repeal Godwin's Law. Drum calls it "an endlessly tiresome way of feigning moral indignation," and Greenwald says, "The very notion that a major 20th Century event like German aggression is off-limits in political discussions is both arbitrary and anti-intellectual in the extreme." Greenwald writes:
There simply are instances where such comparisons uniquely illuminate important truths -- recall, for example, Andrew Sullivan's consequential discovery of the stark similarities between the Bush/Cheney and Gestapo "enhanced interrogation" program, both the tactics and "justifications" -- and to demand that German crimes be treated as sacred and unmentionable is to deprive our discourse of critical truths.
As someone who thinks we should try to avoid inappropriate Nazi comparisons as well as those involving more obscure historical atrocities, I felt compelled to defend it. Godwin's Law is: "As an online discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches 1." That's about as solid as the Law of Gravity; you can't actually repeal it. While Godwin himself thinks Hitler comparisons should be avoided, Godwin's Law is not that you can never bring up the Nazis or Hitler in an argument. What Drum and Greenwald want to get rid of is the notion that once you mention the Nazis, you might as well be Hitler himself.
The thing is, Godwin's Law is not meant to discourage legitimate comparisons between say, torture techniques. A peripheral effect of the law is meant to be that it embarrasses morons who compare trivialities to atrocities, like implying there's a slippery slope between infrastructure projects and Auschwitz. It is meant to preserve the meaningfulness of such a comparison by limiting it to circumstances in which it's actually appropriate. In any case, since such comparisons are rampant, this social prohibition is about as effective as outlawing marijuana.
Honestly, I think we could do with fewer random comparisons of random things we don't like to historical genocides. In part, I think what Drum and Greenwald are talking about is something Jon Chait wrote about a while ago -- our general inability to distinguish between a Nazi comparison and a Nazi analogy, the latter being used to illustrate an actual non-outrageous point that is then bludgeoned to oblivion by someone who chooses not to get the idea.