While the state courts will be able to hear most claims, statutes vary as to which court within the state hears those claims. All states have a trial court of general subject matter jurisdiction that can hear common types of suits. This court may be called the superior court, the circuit court, the district court, or something else, depending on the state. In addition, states usually establish specialized courts to hear some types of cases requiring particular expertise, such as probate courts, municipal courts, land courts, or housing courts. Some of our thirstier western states even have water courts.
The state courts handle by far the greatest part of the judicial business. In 2009, an incredible 106 million cases were filed in the courts of the fifty states. By comparison, 2,174,330 were filed in the federal courts in 2010. The respective numbers of judges also convey a sense of the extent to which state courts carry the laboring judicial oar. As an example, the California state trial courts had about 1,700 judges in 2011, while there were only about 187 federal judges (including bankruptcy judges and magistrates) sitting in the federal courts in California.
Unlike the state courts, which exercise very broad subject matter jurisdiction, the type of cases that federal courts can hear is extremely limited. The subject matter jurisdiction of federal courts is defined in Article III, §2 of the Constitution. Generally speaking, any case not on the Article III, §2 list must be brought in state court: The basic premise of the Constitution is that the federal government has the authority to exercise powers expressly or impliedly granted in the Constitution, but that all others—those not granted to the feds—are reserved to the states or to the people. U.S. Constitution, Amendment X.
Under Article III, s. 2 the federal courts are authorized to hear cases between states, between citizens of different states, between citizens and aliens, cases involving foreign ministers and consuls, admiralty and maritime cases, cases arising under the federal Constitution and federal law, and a few other narrow categories of suits. In each of these types of cases, the framers perceived an important national interest. In cases between states, cases between citizens of different states, and cases between citizens and aliens, for example, they foresaw a risk of prejudice against the outsider—generally, the defendant—in state court. Admiralty and maritime cases and those involving ministers and consuls involve international relations, to which the nation should speak with one voice. Similarly, it makes sense that federal courts should be able to hear cases that involve the application and interpretation of federal law, both to protect it from unsympathetic construction by state courts and to allow definitive interpretation of federal law.