I don't think that is entirely true. For example, if a cheating happens in an online game you don't wait a court decision to ban the player - taking the justice on your hands and expect to not be punished. Or killing a person is illegal but you can use your self-defence rights if the other person is trying to kill you. You can use interfaces from copyrighted language (Oracle v. Google) for fair use purposes without getting a court decision first.

If the thing that you are trying to do is legal by universal laws, international laws and national laws (in order). You don't really need to worry.

In that stealing example let's assume someone stole something and you "stole" it back. Good luck for the first stealer to initiate a court case - which probably the stealer will not initiate because he will lose it plus with the expenses for the court. No court case meaning no complains therefore no crime.