Why not make a contract with your child about drugs, gangs and violent behavior. The parents of those kids on the news are in shock when their little darling is accused of murder. Do not go into denial when you get a hint of problems. The more impartial you are when imposing the consequence, the better the results will be. Do not make angry statements.
Negative comments move the system from loving and fair to nasty and vindictive.
Your children will treat you and the rest of society the way they are treated. It is easier to become successful in life if you are positive rather than negative . Some people avoid saying what they need to say because they are afraid of the results. The outcome is always worse than it would have been. One couple failed to discuss their expectations prior to their marriage.