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 Maryland, the role described as 'justices of the peace' does not exist under that title. Instead, Maryland has a system of District Courts that handle many of the functions mentioned. District Court judges preside over civil cases involving amounts up to $30,000, landlord-tenant disputes, replevin actions (recovery of wrongfully taken or detained goods), and small claims matters, which are typically claims under $5,000. They also handle motor vehicle and boating violations, some misdemeanors, and certain felonies that do not require a jury trial. Additionally, District Court commissioners, who are judicial officers but not judges, issue arrest warrants, set bail, and preside over initial appearances of defendants. For matters such as marriage ceremonies, Maryland law allows clerks, deputy clerks of the Circuit Court, judges, and ordained ministers to perform marriages. The specific duties related to mental health commitments, juvenile warnings, and animal cruelty cases are typically handled by different entities within Maryland's legal system, such as the Circuit Courts, family courts, or administrative agencies.