regular citizens can never know if they're breaking the law, there are so many of them after all, but therein lies an interesting thing. the law is rarely applied based on who is breaking the law, but rather who the person is.
anyone can be singled out and have their life turned upside down by law enforcement, it's all a matter of application. application of the law occurs on people who already have their feet wet and lower socio economic classes.
keep your nose clean and you won't run afoul of the law. I'd say that especially goes for "do no harm to anyone else" areas, that's how you first get in trouble, is if you assault or cause a harm to someone else. that raises your profile initially and from then on the system is inadvertently designed to focus on you and drive you into the ground.
most people get away with all kinds of minor crimes, so long as they don't actually physically or monetarily harm someone else (or be black) you won't get dragged into the undertow of the criminal justice system.