A doctrine that provides a basis for federal question jurisdiction over certain state-law claims. The doctrine applies when a federal statute is so broad that it wholly displaces any state-law claims relating to the same subject matter (Aetna Health Inc. v. Davila, 542 U.S. 200, 207 (2004)). A claim within the scope of the federal statute is therefore based on federal law, even if pleaded in state-law terms. When complete preemption applies, a defendant may remove the pre-empted state-law claims to federal court. (Beneficial Nat'l Bank v. Anderson, 539 U.S. 1, 8 (2003).)

Complete preemption is an exception to the well-pleaded complaint rule. Under the well-pleaded complaint rule, a defendant may not remove a state-law action to federal court on the basis of federal question jurisdiction unless the complaint establishes that the causes of action arise under federal law. This is because courts generally examine only the well-pleaded allegations of a complaint and ignore any potential defenses. (Beneficial Nat'l Bank, 539 U.S. at 6.) Complete preemption essentially transforms state-law claims into claims arising under federal law (Lontz v. Tharp, 413 F.3d 435, 440-41 (4th Cir. 2005)).

The US Supreme Court has held that complete preemption applies to state law claims relating to three federal statutes:

(Sullivan v. Am. Airlines, 424 F.3d 267, 272 (2d Cir. 2005).)

Complete preemption is different from ordinary preemption. Complete preemption is a jurisdictional doctrine that transforms state-law claims into federal claims. Ordinary preemption is a defense whereby the defendant argues that it is not liable for state-law claims because they are pre-empted by federal law (Sullivan, 424 F.3d at 272-73). Ordinary preemption does not provide a basis for removal jurisdiction (Sullivan, 424 F.3d at 273).