> try pleading ignorance of the law when you're arrested for breaching a traffic regulation That won't work for a mundane. However, if you're a cop, and you a

> try pleading ignorance of the law when you're arrested for breaching a traffic regulation That won't work for a mundane. However, if you're a cop, and you arrest someone under the pretext that it's for driving without a seat belt (max penalty $50 fine), judges might decide that your disregard of the law was mere ignorance and take that as an excuse. https://en.wikipedia.org/wiki/Atwater_v._Lago_Vista https://en.wikipedia.org/wiki/Atwater_v._Lago_Vista