The land now known as Missouri once was under the control of Spain, then France, until the young United States of America acquired it as part of a large swath of land in the 1803 Louisiana Purchase. In 1812, settlers organized Missouri as its own territory apart from the Louisiana territory. It also established a system of courts to resolve disputes.

The highest court in the territorial system – rather like the state's supreme court today – was called the superior court. It had three judges, and it had both original and appellate jurisdiction in civil and criminal cases.

Similar to today's trial courts were the inferior courts. By 1815, the territory had two inferior courts.

The territorial judicial system also relied on a number of justices of the peace, who were available throughout the territory to help resolve disputes.

Missouri modeled its territorial judicial system after French and Spanish civil law, but that influence waned as attorneys from the east crossed the Mississippi River into Missouri. In January 1816, the territorial legislature adopted the English common law as Missouri's official law.