There is also the possibility of getting stopped for speeding even if you are UNDER the limit. In poor weather and road conditions you can be cited for driving too fast for conditions, and that is totally at an officers discretion. The limit posted is for “normal driving conditions”.
In most places you can; very few no.
Our photo radar on State roads here in AZ won’t snap your picture until you are 11mph over. It is all different with the City