Godwin’s Law (also Godwin’s Rule of Nazi Analogies) is a mainstay of Internet culture, an adage formulated by Mike Godwin in 1990. It is particularly concerned with logical fallacies such as reductio ad Hitlerum, wherein an idea is unduly dismissed or rejected on ground of it being associated with persons generally considered “evil".

The law states:

Godwin’s Law
As an online discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches one.

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 argues in his book, Cyber Rights: Defending Free Speech in the Digital Age, that hyperbolic overuse of the Hitler/Nazi comparison should be avoided, as it robs the valid comparisons of their impact.