Michigan v. Long
Citation: 463 U.S. 1032 (1983) Court: United States Supreme Court
Facts
David Long was stopped by police during a traffic stop and officers observed a hunting knife in the car. During a protective search of the passenger compartment (a “Terry frisk” of the car), officers found marijuana under the armrest. Long was convicted of possession. The Michigan Supreme Court reversed, citing both the federal 4th Amendment and the Michigan Constitution. The State sought U.S. Supreme Court review.
Issue
When a state court decision appears to rest on both federal and state constitutional grounds, does the U.S. Supreme Court have jurisdiction to review the decision? And on the merits, was the protective vehicle search lawful?
Holding
On jurisdiction: Yes, the Supreme Court has jurisdiction when the state court decision rests on federal grounds, unless the court expressly states it is relying on adequate and independent state law. On the merits: The search was lawful under Terry v. Ohio.
Rule / Doctrine
Adequate and Independent State Ground (AISG) doctrine: The U.S. Supreme Court will not review a state court decision that rests on an adequate and independent state law ground, because such a ruling would be an advisory opinion. However, when a state court decision appears to rest on federal law — or its meaning is unclear — the Supreme Court will assume it has federal jurisdiction. To avoid Supreme Court review, a state court must make a plain statement that its decision rests on state law grounds that are independent of, and adequate to support, the judgment.
Significance
Michigan v. Long established the “plain statement” rule that governs the AISG doctrine. It clarified the allocation of review authority between state and federal courts and gave state courts a clear mechanism to render their decisions unreviewable by the U.S. Supreme Court (by expressly invoking independent state grounds). The case is centrally important in both Federal Courts and Conflict of Laws courses for its treatment of federal jurisdiction and federalism.