Federal common law is a narrow body of judge-made rules that federal courts create in the handful of areas where a uniform national rule is genuinely necessary and Congress has not supplied one. It is not a general power to invent law. Since 1938, federal judges have been barred from crafting broad legal principles for ordinary disputes, and what survives is a small set of specialized enclaves — interstate controversies, foreign affairs, admiralty, the federal government’s commercial dealings, and certain constitutional remedies — each defended on the ground that letting fifty states set their own rules would frustrate a federal interest.
Why the Doctrine Is So Narrow
The modern shape of federal common law is defined by what federal courts cannot do. In Erie Railroad Co. v. Tompkins, the Supreme Court declared that “there is no federal general common law.”1Federal Judicial Center. Erie Railroad Co. v. Tompkins (1938) Federal courts hearing diversity cases must apply the law of the state whose courts would otherwise decide the dispute, whether that law comes from a statute or a state court decision.2Library of Congress. Erie Railroad Co. v. Tompkins, 304 U.S. 64 (1938)
The statutory backbone is the Rules of Decision Act, 28 U.S.C. § 1652, which directs federal courts to treat state laws as rules of decision “in cases where they apply,” except where the Constitution, a treaty, or a federal statute says otherwise.3Office of the Law Revision Counsel. 28 USC 1652 – State Laws as Rules of Decision That exception is the crack through which federal common law still enters. A court invoking it has to show that state-by-state variation would genuinely frustrate a federal interest, and judges who stretch the authority beyond its boundaries get reversed.
No Federal Common Law Crimes
One boundary matters enough to state up front: there is no such thing as a federal common law crime. No one can be convicted of a federal offense unless Congress has defined that offense by statute. The Supreme Court settled this in 1812 in United States v. Hudson and Goodwin, holding that “the legislative authority of the Union must first make an act a crime, affix a punishment to it, and declare the Court that shall have jurisdiction of the offence.”4Legal Information Institute. The United States v. Hudson and Goodwin
Federal judges retain inherent powers no court could function without, such as punishing contempt. But criminal jurisdiction over conduct in the outside world belongs to Congress alone. Today, 18 U.S.C. § 3231 limits federal court jurisdiction to “offenses against the laws of the United States,” which reinforces that every federal prosecution must rest on an act of Congress.5Office of the Law Revision Counsel. 18 U.S. Code 3231 – District Courts
Where Federal Common Law Still Operates
Disputes Between States
When states fight over borders, rivers, or other shared resources, no single state’s law can supply a neutral answer. The Constitution gives the Supreme Court original jurisdiction over “Controversies between two or more States,” and federal common law fills in the substantive rules.6Constitution Annotated. ArtIII.S2.C1.12.1 Overview of Admiralty and Maritime Jurisdiction Water allocation is the most frequent flashpoint. The Court applies a doctrine called equitable apportionment, balancing each state’s needs based on historical usage, current demand, conservation efforts, and available alternatives, rather than handing everything to whichever state got there first. Kansas v. Colorado is among the most prominent examples.7Justia. Kansas v. Colorado, 514 U.S. 673 (1995) A state that takes more than its share can face an injunction or an order to pay damages.
Foreign Affairs
The federal government speaks for the entire country in foreign affairs, and federal common law protects that monopoly from state-level interference. The clearest example is the act of state doctrine, articulated as a matter of federal law in Banco Nacional de Cuba v. Sabbatino. American courts “will not examine the validity of a taking of property within its own territory by a foreign sovereign government, extant and recognized by this country at the time of suit.” The Court called the doctrine “exclusively an aspect of federal law” because it concerns “the competence and function of the Judiciary and the National Executive in ordering our relationships with other members of the international community.”8Justia. Banco Nacional de Cuba v. Sabbatino, 376 U.S. 398 (1964)
Federal common law also shapes claims brought under the Alien Tort Statute, 28 U.S.C. § 1350, which gives federal courts jurisdiction over civil suits by aliens for torts “committed in violation of the law of nations.” In Sosa v. Alvarez-Machain, the Supreme Court held that the statute is jurisdictional only. Courts may recognize claims under federal common law, but only for violations of international norms with a level of “definite content and acceptance among civilized nations” comparable to the 18th-century paradigms Congress had in mind: offenses against ambassadors, violations of safe conducts, and piracy.9Justia. Sosa v. Alvarez-Machain, 542 U.S. 692 (2004) The Court told judges to exercise “great caution” before recognizing anything new.
Admiralty and Maritime Law
Maritime law is the oldest and most developed enclave of federal common law. The Constitution extends federal judicial power to “all Cases of admiralty and maritime Jurisdiction,” and federal courts have exercised that authority since the founding to build a specialized body of rules governing commerce and injuries on navigable waters.6Constitution Annotated. ArtIII.S2.C1.12.1 Overview of Admiralty and Maritime Jurisdiction The rationale is practical. A cargo ship traveling from Houston to Rotterdam shouldn’t face different liability rules every time it enters a new port.
Among the most consequential judge-made rules here is the warranty of seaworthiness, which requires vessel owners to provide a ship reasonably fit for its intended use. This is not a negligence standard. Courts have described it as “a species of liability without fault” that is “neither limited by conceptions of negligence nor contractual in character.”10University of Florida Law Review. Recent Developments in the Doctrine of Unseaworthiness Injured crew members are also entitled to maintenance and cure, a judge-made obligation covering daily living expenses and medical treatment until the worker reaches maximum medical improvement. A civil action for personal injury or death arising from a maritime tort must be brought within three years of the cause of action.11Office of the Law Revision Counsel. 46 USC 30106 – Time Limit on Bringing Maritime Action for Personal Injury or Death
The Federal Government as a Commercial Actor
When the federal government writes checks, issues bonds, or enters into contracts, those transactions cross every state line. In Clearfield Trust Co. v. United States, the Supreme Court held that when the United States “disburses its funds or pays its debts, it is exercising a constitutional function or power” and that its rights and duties on commercial paper “are governed by federal, rather than local, law.”12Justia. Clearfield Trust Co. v. United States, 318 U.S. 363 (1943) The Court warned that applying different state laws would “subject the rights and duties of the United States to exceptional uncertainty.”13Legal Information Institute. Clearfield Trust Co. v. United States
The same principle extends to disputes over federal contracts. A contractor building a bridge in Montana and one building a bridge in Georgia face the same legal standards when dealing with the federal government. Clearfield also grounds the government contractor defense, recognized in Boyle v. United Technologies Corp. When a private contractor builds military equipment to the government’s own specifications, state tort law that would impose liability for design defects is displaced if the government approved reasonably precise specifications, the equipment conformed to those specifications, and the contractor warned the government about known dangers the government was not aware of.14Justia. Boyle v. United Technologies Corp., 487 U.S. 500 (1988)
Constitutional Remedies Against Federal Officers
Federal common law also created — and now sharply limits — the right to sue federal officers for damages when they violate the Constitution. In Bivens v. Six Unknown Named Agents, the Supreme Court held in 1971 that a person whose Fourth Amendment rights were violated by federal narcotics agents could sue for money damages even without a statute authorizing the suit. The Court reasoned that “where federally protected rights have been invaded, it has been the rule from the beginning that courts will be alert to adjust their remedies so as to grant the necessary relief.”15Justia. Bivens v. Six Unknown Fed. Narcotics Agents, 403 U.S. 388 (1971)
The Court has spent the last half-century pulling back. Recognizing a new Bivens cause of action is now “a disfavored judicial activity.” Courts apply a two-step test: whether the case is “meaningfully different” from the three situations where Bivens has already been recognized, and whether any “special factors” suggest that Congress rather than the judiciary should decide whether a damages remedy is appropriate. A single reason to defer to Congress is enough to block the claim, and the existence of any alternative remedial process — an internal grievance system, an inspector general — counsels against allowing the suit even if the alternative is less effective.16Supreme Court of the United States. Egbert v. Boule (2022) In practice, Bivens claims now succeed almost exclusively in cases that look nearly identical to the 1971 original.
Congress Can Shut It Down
Every enclave described above is provisional. Federal common law exists only because Congress has left the space unfilled, and once Congress addresses the same subject, the judge-made rule gives way. As the Supreme Court put it in City of Milwaukee v. Illinois, “when Congress addresses a question previously governed by a decision rested on federal common law the need for such an unusual exercise of lawmaking by federal courts disappears.”17Library of Congress. Milwaukee v. Illinois, 451 U.S. 304 (1981)
The threshold for displacement is lower than the one for preempting state law. Congress doesn’t have to say explicitly that it is replacing a judge-made rule. The test is whether the statute “speaks directly to the question” at issue.18Justia. American Electric Power Co. v. Connecticut, 564 U.S. 410 (2011) In American Electric Power Co. v. Connecticut, states and environmental groups sued power companies under federal common law nuisance for greenhouse gas emissions. The Supreme Court held unanimously that the Clean Air Act displaced the claim because it delegated the question of carbon dioxide regulation to the EPA. That the EPA hadn’t yet issued specific emissions standards didn’t matter; Congress had assigned the decision to the agency, and that delegation was enough to push federal common law out of the picture. The “complex balancing” of environmental, energy, and economic concerns belongs to an expert agency rather than to federal judges improvising under tort law.