Not morality
The choice essentially boils down to: Will a person follow the rules of society or their own morals? Say you capture a criminal, but due to his connections he gets off scot free. The Lawful thing to do would be to just capture him again, knowing nothing will happen to him. A 'Good' person will do everything they can to ensure he gets justice, regardless of law. Essentially, it boils down to whether you think either "Truth and Justice" (Good) or "following society's rules" (Law) is more important,