The difference between fighting one of these tickets and a speeding ticket for going over the speed limit is that here the prosecution has the burden of proving you were driving unsafely. (Again, that's because the posted speed limit is presumed to be safe.) This means the officer must testify that, given the unusual road, weather, or traffic conditions, your below-the-limit speed was unsafe. This can be tough to do unless you were involved in an accident, since the cop may be hard put to come up with enough hard evidence to rebut the presumption established by the posted limit.

Police most often rely on the "basic" speed law after an accident. They reason that you were driving too fast, no matter how slow you were driving, because you were in an accident. However, you do not have to despair if you were in an accident and are charged with violating the "basic" law for driving at an unsafe below-the-limit speed. The fact that you've had an accident is not absolute proof that you were driving unsafely. Accidents, after all, are not always caused by your violating the law. Often they are caused when another driver screwed up.