Quote Originally Posted by Phantaroth
It is a bad rule as bringing up Nazis is a valid point in an argument.
"Godwin's Law does not dispute whether, in a particular instance, a reference or comparison to Hitler or the Nazis might be apt. It is precisely because such a reference or comparison may sometimes be appropriate, Godwin has argued, that overuse of the Hitler/Nazi comparison should be avoided, as it robs the valid comparisons of their impact."

http://en.wikipedia.org/wiki/Godwin%27s_law