Many legal systems throughout the world retain the use of Latin words or phrases which originated centuries ago in the legal system of ancient Rome. The term "suo moto" is one of those terms. Literally translated, suo moto means "on its own motion." The term generally refers to a situation wherein a judge acts without request by either party to the action before the court.

Under normal proceedings before a court, a judge's role is to direct the proceedings and act on motions filed with the court. When a party to a court case wants the judge to rule on an issue, or make a decision regarding something pertinent to the case, he or she files a motion with the court. The opposing party then has an opportunity to respond to the motion before the judge rules on the motion. In some cases, a judge acts suo moto, meaning without one of the parties' asking him or her to do so.

One common example of when a judge may act suo moto is when he or she decides that he or she does not have personal or subject matter jurisdiction over the case before him or her. In other words, the judge decides that he or she does not have the legal authority to preside over the case. In that case, the judge may make a motion, without either party asking him or her to do so, moving the case to another jurisdiction or dismissing the case for lack of jurisdiction.

A judge may also act suo moto in a domestic case, such as a divorce or child custody case. Often, minor children are the subject of a domestic or family law case that comes before a judge. When the parents are battling over custody of the minor children and the judge feels that the best interest of the children is being overlooked, he or she may move to appoint a guardian ad litem. A guardian ad litem's role in the judicial system is to represent the best interests of the child throughout the proceedings.

In a criminal case, a judge may act suo moto as well. The judge may decide that a jury instruction is necessary that was not requested by the parties. The judge may also request that the jury members be polled to assure him or her that the verdict was unanimous after returning the verdict without either party asking him or her to do so.