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 Illinois, the role described as 'justices of the peace' does not exist in the same form as it might in other states. Illinois does not have justices of the peace; instead, it has a circuit court system with judges who handle legal matters. The circuit courts in Illinois are the trial courts of the state and have general jurisdiction over civil and criminal cases. Small claims, evictions, and other civil matters are typically handled by associate or circuit judges in the respective county circuit courts. Criminal misdemeanors would also be addressed within this court system. Administrative hearings may be conducted by administrative law judges or hearing officers, depending on the context. Duties such as presiding over certain types of hearings, issuing warrants, and conducting trials are performed by circuit court judges or administrative law judges. Marriage ceremonies can be performed by judges, as well as certain other officials and persons authorized by the state. It's important to note that the specific procedures and the allocation of duties can vary by county within Illinois.