Each state’s constitution and laws establish the state’s courts, which interpret state laws (and generally not federal laws). A court of last resort, often known as a supreme court, is usually the highest court in the state. Some states also have an intermediate court of appeals. Below these intermediate courts of appeal are the state trial courts, where most lawsuits begin. State trial courts are referred to differently in different states—often as district courts, circuit courts, or superior courts.

State courts are often courts of general jurisdiction—meaning they hear all types of cases—involving criminal law, family law, probate law, and general disputes involving money and property. But more populated counties often have courts of specific jurisdiction, such as family courts that only hear family law matters (divorce, child custody, child support); criminal courts that only hear criminal matters; and probate courts that only handle the probate of estates and related litigation.

In Oklahoma, the judicial system is structured with the Oklahoma Supreme Court serving as the court of last resort for civil matters, and the Oklahoma Court of Criminal Appeals as the highest court for criminal cases. There is no intermediate court of appeals; instead, the Oklahoma Supreme Court can assign certain appellate cases to the Oklahoma Court of Civil Appeals for review. At the trial level, Oklahoma has District Courts that serve as the state trial courts of general jurisdiction. These courts handle a wide range of cases, including criminal, family, probate, and general civil disputes. In more populated counties, there may be specialized divisions within the District Courts that focus on specific areas of law, such as family law or probate matters. These specialized divisions streamline the legal process by concentrating expertise and resources on particular types of cases.