Actually, that's "strict liability".
> All that needs to be proven is that you were, in fact, speeding. It doesn't matter if you could not have been aware of your violation due to, say, a speed-limit sign that was blown away by a storm.
That probably does matter, since exceeding the speed limit properly posted is usually the actus reus of speeding, so even to the extent it is a strict liability offense, the absence of proper signage for any reason (except when the speed limit is either the states maximum highway speed limit or a default limit for some other condition which does not require signage, in which case notice is provided by the law setting the default for the conditions, and the sign is a reminder) makes it so that no offense occurred. [0]
[0] Also, given that states do generally have default speed limits that apply in the absence of signage, one could easily argue that the absence of signage is itself a positive indication that the default speed limit applies, making available a U.S. v. Kantor-style "good faith" defense even under strict-liability principles. [1]
[1] https://en.wikipedia.org/wiki/Strict_liability_(criminal)#Un...
