A person who flouts the law, esp. by failing to comply with a law that is difficult to enforce effectively.
There’s something that’s been puzzling me. How effective is a law likely to be in changing the behavior of someone who is, by definition, a scofflaw? I.e., membership in the class of individuals whose behavior you’re trying to change implies that the individual is a scofflaw; they can’t be included in the class without being one.