Clearfield trust doctrine refers to the rule describing the federal courts’ power to make federal common law when there is a federal lawmaking power to do so and a strong federal interest in a nationally uniform rule. The name is derived from the case Clearfield Trust Co. v. United States, 318 U.S. 363 (U.S. 1943) wherein the criteria for determining whether the court should create a federal common law rule due to the existence of a significantly important federal interest was described. The three criteria are:

Is there a federal competence to create law in this area?

If there is federal competence, should state or federal law govern?

If federal law governs, should courts borrow state law or create a new federal rule?