Justices of the peace are judges who handle both civil and criminal cases, including small claims court, justice court, and administrative hearings. In practical terms, these are lawsuits over debts, evictions, car accidents, unlawful towing, and property.

Their criminal workload involves disposing of all class C criminal misdemeanor complaints, such as traffic citations, issuance of bad check, and others. These cases involve payment, setting contested cases for trial, and pretrial hearings with the county prosecutor.

Other duties include presiding over peace bond hearings, reviewing applications for mental health or chemically dependent commitments, conducting compulsory school attendance trials, and giving warnings to juveniles required by law. They issue warrants for and conduct hearings concerning seizure and disposition of cruelly treated animals. Most justices of the peace perform marriage ceremonies as well.

In California, the role described as 'justices of the peace' does not exist in the same form as it might in other states or historical contexts. Instead, California has a system of Superior Courts that handle both civil and criminal cases. Small claims cases, evictions, and other civil matters are typically handled by commissioners or judges in the Superior Courts. Traffic citations and other misdemeanors are also addressed within the Superior Court system, often in specialized departments or courts, such as traffic court. California does not have justices of the peace who handle class C misdemeanors, as California's criminal offenses are categorized differently. Duties such as presiding over certain hearings, issuing warrants, and conducting trials related to school attendance or animal cruelty would fall under the jurisdiction of the Superior Court or relevant administrative bodies. Marriage ceremonies can be performed by judges, commissioners, and some other officials authorized by California law. It's important to note that the specific procedures and the allocation of these duties can vary by county within California.