scofflaw [skawf-law, skof-]
North American, informal
1 A person who flouts the law, especially by failing to comply with a law that is difficult to enforce effectively, especially one who fails to pay debts or answer summonses
2 A person who often breaks the law but in a way that is not very serious.
3 A person who flouts rules, conventions, or accepted practices.
The Illinois State Toll Highway Authority unanimously approved a three-year, $38 million contract with a private firm to catch toll scofflaws. (Toll Cheaters Beware)
So really, instead of calling cyclists scofflaws, drivers should look in the mirror. (Lloyd Alter, New study shows that "scofflaw cyclists" don't break the law any more than drivers)
In 1924, a wealthy Massachusetts Prohibitionist named Delcevare King sponsored a contest in which he asked participants to coin an appropriate word to mean 'a lawless drinker.' King sought a word that would cast violators of Prohibition laws in a light of shame. Two respondents came up independently with the winning word: scofflaw, formed by combining the verb scoff and the noun law. Henry Dale and Kate Butler, also of Massachusetts, split King’s $200 prize. Improbably, despite some early scoffing from language critics, scofflaw managed to pick up steam in English and expand to a meaning that went beyond its Prohibition roots, referring to one who violates any law, not just laws related to drinking. (Merriam-Webster)