A guardian ad litem is a competent person appointed by the court for the purpose of a particular action or proceeding. This appointment is often for cases involving a minor or a person alleged to be incompetent. The court where the case is pending appoints the guardian ad litem.

The role of a guardian ad litem is to assist a minor or an incompetent person who may sue or be sued. If a party becomes incompetent or incapacitated during a case, the court may allow the action to continue against that party, assisted by a legal guardian or guardian ad litem. When the heir of a deceased party is a minor, the court may appoint a guardian ad litem for the minor heir. Service of summons upon a minor, insane, or incompetent defendant who has no legal guardian is made upon them personally and upon their guardian ad litem; the plaintiff applies for this appointment. A copy of the complaint and the order for the appointment of a guardian ad litem, if any, is attached to the summons.

Guardian ad litems may act on behalf of their ward in proceedings such as partition of real estate, with court approval. In expropriation proceedings, a guardian or guardian ad litem of a minor or person judicially declared incompetent may, with court approval, perform acts respecting the expropriation of the ward's property. The counsel and guardians ad litem in the court where the case originated are considered their counsel and guardians ad litem in the Court of Appeals. For a child witness in a crime case, a guardian ad litem is appointed by the court to protect the child's best interests.