How is the idea of federalism applied to the court system?

The doctrine of "subject-matter jurisdiction".

Explanation:

The thought of federalism is applied to and in the state court and federal court systems in the United States by the doctrine of "subject-matter jurisdiction".In the US federalism Judicial system has parallel courts: state courts and federal courts.because of this, it is important to know which court has jurisdiction, to the authority to hear certain cases in legal matters. In the U.S. federal courts, subject-matter jurisdiction is a matter of two general types as set forth in the Judicial Code:diversity jurisdiction.federal-question jurisdiction.