Supplemental Jurisdiction

What It Is

Supplemental jurisdiction (28 U.S.C. § 1367) allows federal courts to hear state law claims that are part of the same “case or controversy” as a federal claim. If you’re suing under § 1983 (federal) and also have state law claims for assault, false imprisonment, or intentional infliction of emotional distress arising from the same incident, you can bring everything in one federal case.

Why Use It

• Efficiency: One case, one court, one trial
• Consistency: The same judge evaluates all claims based on the same facts
• Strategy: State claims may have lower standards or additional remedies not available under § 1983

The Risk

Under § 1367(c), the court may decline supplemental jurisdiction if:

• The state claims raise novel or complex questions of state law
• The state claims substantially predominate over the federal claims
• The court has dismissed all federal claims
• There are other compelling reasons

The most common scenario: Your § 1983 claims get dismissed on qualified immunity or at the motion to dismiss stage. The court then declines supplemental jurisdiction over your state claims and dismisses them without prejudice. You have to refile in state court — and the statute of limitations may have run.

§ 1367(d) provides a 30-day tolling period after dismissal to refile state claims in state court. But 30 days goes fast.

Practical Advice

• Plead state law claims as backup to your § 1983 claims
• Be aware that if federal claims fail, state claims may get kicked
• Watch the 30-day refiling window if state claims are dismissed
• Consider filing in state court from the start if your state claims are stronger than your federal claims

Key Cases

• Carnegie-Mellon University v. Cohill, 484 U.S. 343 (1988) — Courts have discretion to remand supplemental state claims
• City of Chicago v. International College of Surgeons, 522 U.S. 156 (1997) — Supplemental jurisdiction over state administrative review claims