Subject matter jurisdiction describes the power of a court to hear a particular kind of case.  A court may have original subject matter jurisdiction over a particular kind of case, appellate jurisdiction, or both.  Article III of the Constitution lists the range of judicial power that a federal court may exercise through subject-matter jurisdiction.  Thus, Congress cannot expand federal subject matter jurisdiction beyond the limits in Article III.  Subject matter jurisdiction is significantly more limited in U.S. federal courts.  The most important two categories of federal subject matter jurisdiction in non-criminal cases are federal question jurisdiction and diversity jurisdiction.  28 U.S.C. § 1331 provides that the district courts have subject matter jurisdiction in all civil actions arising under the Constitution, laws, or treaties of the United States.  However, this jurisdiction is ordinarily not exclusive because states also can hear claims based on federal law.

A court has subject-matter jurisdiction if:

• A federal statute confers jurisdiction on the court; and
• The grant of jurisdiction is constitutional.

A federal court must dismiss a case for lack of subject-matter jurisdiction upon motion of a party, upon its own initiative according to Rule 12(h)(3) of the Federal Rules of Civil Procedure.  In federal criminal cases, 18 U.S.C. § 3231 grants subject matter jurisdiction to federal district courts.