- A Latin legal term referring to someone appointed by the court to act in a lawsuit on behalf of another party who is deemed incapable of representing themselves, such as a child or mentally incompetent person. This person's role ends when the lawsuit is over or when the person being represented comes of age or regains capacity
- The court appointed a guardian ad litem for the child to ensure her interests were protected during the custody dispute.
- Due to his mental health issues, an ad litem was appointed to represent him in court.
- She was assigned as ad litem to fight for the rights of the incapacitated elderly man during the trial.