The justice court and state courts decide legal questions in Marion County.  The justice court is funded by the county. Minor traffic offenses, fish and game offenses, and small civil claims are heard in this court. In addition the justice court hears cases relating to violations of county ordinances, such as charges of excessive noise or dogs running at large.

The Justice Court is the county equivalent of the municipal courts which exist in larger cities such as Salem.

Most misdemeanors, all felonies, and most civil cases are heard in the  state court which is located in the Marion County Courthouse. State judges also conduct hearings at the Marion County Correctional Facility and at the Marion County Juvenile Department.

These courts are under the administrative authority of the State of Oregon which pays the salaries of the 13 elected judges and their staff. Marion County provides space for offices, jury assembly, and courtrooms. The Marion County Sheriff's Office is responsible for court security, prisoner transport and service of warrants and other court papers.