Also known as: adjective laws · procedural law
Written by attorneys · grounded in primary & secondary sources — see below
The body of rules governing procedure and practice. It encompasses the remedial agencies and methods by which rights are maintained, their invasion redressed, and the methods by which such results are accomplished in judicial tribunals.
Adam Anderson filed a diversity suit against Apex Dynamics in federal court sitting in State X. The court applied federal rules to determine the validity of service on the defendant's registered agent. That procedural step proceeded under federal adjective law even though the underlying contract claim followed State X substantive rules.
Angela Acosta sued Apollo Energy after an on-site injury. The federal court ordered her to submit to a physical examination under the applicable federal rule. The order was treated as a matter of adjective law that the court could enforce without altering substantive rights.
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Aaron Adams commenced a diversity action against Arcadia Retail in federal court. The defendant moved to dismiss for untimely service under state practice. The court applied the federal rule governing service because it was adjective law that controlled the manner of proceeding.
Abigail Alvarez brought a state-law claim in federal court under diversity jurisdiction. The court looked to state law to decide whether the action was timely. That outcome-determinative rule was classified as substantive rather than adjective law.
Andrew Avery filed a contract action against Azure Solutions that was referred to a bankruptcy court. The court declined to adjudicate the state-law claim because its authority was limited to matters properly classified as procedural under federal adjective law.
Arthur Abrams moved to suppress evidence obtained during a search in his federal criminal case. The court applied federal procedural standards to decide admissibility. Those standards constituted adjective law that governed the conduct of the proceeding.
Adjective law consists of the rules that govern procedure and practice in court. Substantive law declares the rights and duties of persons subject to the law. The distinction determines whether a federal court in diversity applies state or federal rules.
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Yes. Rules governing the manner and timing of service are classic examples of adjective law because they regulate how litigation proceeds rather than the underlying rights asserted.
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Federal courts may adopt procedural rules that incidentally affect litigants' rights, but they may not use adjective law to alter substantive rights created by state law.
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The distinction controls whether the federal court applies state substantive law or federal procedural rules. This prevents forum shopping and ensures that the outcome in federal court mirrors the result that would obtain in state court.
…of Erie was therefore identical to that of the Enabling Act: federal courts are to apply state substantive law and federal procedural law. However, as subsequent cases sharpened the distinction between substance and procedure, the line of cases following Erie diverged markedly from the line construing the Enabling Act.…