Propriety

From Spanking Art
You can deny all you want that there is etiquette, and a lot of people do in everyday life. But if you behave in a way that offends the people you're trying to deal with, they will stop dealing with you...There are plenty of people who say, 'We don't care about etiquette, but we can't stand the way so-and-so behaves, and we don't want him around!' Etiquette doesn't have the great sanctions that the law has. But the main sanction we do have is in not dealing with these people and isolating them because their behavior is unbearable.
  — Miss Manners (Judith Martin), 1995

Propriety means correct or appropriate behavior. The corresponding adjective is proper.