Can federal courts exercise supplemental jurisdiction over state law claims?

Federal courts can indeed exercise supplemental jurisdiction over state law claims if those claims are related to claims that fall within the court's jurisdiction. This concept is grounded in the notion that if a federal court has the authority to hear a federal claim, it can also hear additional state law claims that are part of the same case or controversy.

The reasoning behind this is to promote judicial efficiency by allowing related issues to be resolved in a single forum, thereby avoiding multiple lawsuits and contradictory results. For instance, if a plaintiff files a federal lawsuit and raises state law claims that are factually connected to the federal claims, the federal court can assert supplemental jurisdiction to hear those state law issues as well.

This principle is encoded in 28 U.S.C. § 1367, which allows federal courts to exercise supplemental jurisdiction over all other claims that are so related to the claims in action that they form part of the same case or controversy under Article III of the United States Constitution. This underscores the importance of connectedness in ensuring that related legal disputes are resolved together.