Esther Hobart Morris was the first woman justice of the peace in the United States. She began her tenure as justice in South Pass City, Wyoming, on February 14, 1870, serving a term of nearly 9 months. The Sweetwater County Board of County Commissioners appointed Morris as justice of the peace after the previous justice, R. S. Barr, resigned in protest of Wyoming Territory's passage of the women's suffrage amendment in December 1869.

A justice of the peace (JP) is a judicial officer of a lower court, elected or appointed by means of a commission to keep the peace. In past centuries the term commissioner of the peace was often used with the same meaning. Depending on the jurisdiction, such justices dispense summary justice or merely deal with local administrative applications in common law jurisdictions. Justices of the peace are appointed or elected from the citizens of the jurisdiction in which they serve, and are usually not required to have any formal legal education in order to qualify for the office. Some jurisdictions have varying forms of training for JPs.