What would be a single word or phrase to describe someone who disregards society and its unwritten rules?
Solution 1:
Rebel - noun - A person who resists or defies authority or convention.
Rebel - noun - A person who does not like rules or authority, and shows this by behaving differently from most people in society.
Rebel - noun - Someone who may behave differently from other people and has rejected the values of society or of their parents.
One classic example is the film James Dean - Rebel Without A Cause. This film is a coming of age story about a young man who rebuffs societal norms and the expectations of his parents on his path to maturity.
The word rebel has become the optimum word choice for North American English speakers who are trying to characterize a person who disregards society norms.
Solution 2:
Non-conformist would be my choice as it does not have as strong connotation to proactive resistance to norms, just someone who pays them no heed. I would say a rebel would wear the opposing team's uniform to a football game whereas a nonconformist wouldn't wear any team's uniform and might be reading a book during the game.
Solution 3:
A recusant TFD
A dissenter; a nonconformist.
Solution 4:
How about "anti-authority"? Someone who is anti-authority has a disregard for rules. You could also say "He is a law unto himself". [https://dictionary.cambridge.org/dictionary/english/be-a-law-unto-yourself][1]
to behave in a way that is independent and does not follow the usual rules for a situation: Charlie, of course, never fills in the record forms but then he's a law unto himself.