The crossword solutions for the term CHALLENGE, LEGALLY are SUE, which is a three letter word. The term 'SUE' is a legal term that refers to the process of bringing a civil lawsuit against another person or entity in a court of law. It is a way of seeking justice and compensation for a wrong that has been done. In a civil lawsuit, the plaintiff (the person who brings the suit) must prove that the defendant (the person being sued) is legally responsible for the harm that has been done.