380 U.S. 460 (1965)
Hanna v. Plumer is a landmark case in the domain of civil procedure, intricately exploring the intersection of state and federal law.
Does Federal Rule of Civil Procedure 4(d)(1) govern service of process in diversity cases, thereby overriding conflicting state procedural requirements under the Erie Doctrine?
In a federal court, Federal Rules of Civil Procedure apply to procedural issues unless they infringe upon substantive rights or are not within the scope of the Rules Enabling Act. If a valid federal rule applies, it will govern despite conflicting state law.
The Supreme Court held that the Federal Rule of Civil Procedure 4(d)(1) applied to service of process, and it trumped the Massachusetts law on service. The Court reversed the lower court's dismissal, maintaining the supremacy of federal procedural rules in diversity cases.
Hanna v. Plumer is significant as it reinforces the clear distinction between substantive and procedural law under the Erie Doctrine, emphasizing the priority of federal procedural rules in diversity cases. It serves as a fundamental case for law students learning about the doctrine's application and the interpretation of procedural versus substantive issues, shaping the understanding of jurisdictional application and the intricate balance between state and federal court powers.