Why Isn't There Just One Court System?
In this country, we have two major court systems (federal and state) and numerous minor court systems (such as bankruptcy, admiralty, and military). Why do we have such a fragmented system? The framers of the Constitution wanted to create a third branch of the government, equal to the others. This is the federal judiciary. At the same time, they feared overreaching federal power, so they limited the power, or jurisdiction, of the federal courts. This has led to a dual court system, with each having its own key role.
There are certain matters that would not be amenable to state courts. Among these are disputes between states, disputes between foreign counties or foreign citizens and U.S. states or citizens, and matters that deal with federal laws and the Constitution. For the most part, the federal courts deal with issues that span multiple states, such as large lawsuits against and between corporations. Similarly, they tend to address interstate crime, like kidnapping or sex trafficking. However, the federal courts authority to hear matters is limited by Article III of the Constitution and subsequent limits set by Congress.
Every matter not handed by the relatively limited federal courts is handled in the state courts. This includes family law issues, landlord-tenant disputes, probate cases, lawsuits between parties within a single state, and nearly all state criminal offenses.
A major benefit to this system is that local courts are better able to shape their laws, decisions, and resources to fit the needs of their local communities. Whereas citizens of Los Angeles, California might have a need to reduce murder rates and fight gang violence, citizens of a small southern college town like Lexington, Virginia may be more concerned with students' misbehavior and small time drug offenses.
While nearly every legal issue that citizens will deal with will be handled by either the state or federal courts, there are specialty courts in place for certain matters. Bankruptcy courts are a distinct branch of the federal system. Military courts are completely independent from state and federal courts and have their own rules of procedure and applicable laws.