A bill of attainder is a legislative act that harms the life or property of specifically identified persons or groups. It declares a specific person or group of persons (e.g., someone's children) to be guilty of a crime without a trial.
In the common law of England before the American Revolution, bills of attainder condemned specific persons to death. The Framers of the Constitution wanted to end that, and prohibited both the federal government (Article I, Section 9, Clause 3) and the states (Article I, Section 10, Clause 1) from passing bills of attainder under the doctrine of separation of powers. The Founders felt so strongly about this that bills of attainder and ex post facto laws are the only laws that the original Constitution prohibits both the federal government and states from ever passing.
Chief Justice John Marshall expanded the prohibition against bills of attainder beyond protection of life to protection of property also in Fletcher v. Peck (1810). However, the Supreme Court has not invalidated any bills of attainder since 1965. The Court will invalidate such law only if the legislation identifies the affected persons and punishes them without a judicial trial.
The Supreme Court viewed the ban on bills of attainder as essential to preserve the separation of powers. The judiciary protects its branch of government by ensuring that only a court can determine the guilt or innocence of an accused. In Cummings v. Missouri (1867), the Supreme Court held that the Congress may not "exercise the power and office of judge." In United States v. Brown (1965), the Court prohibited "legislative punishment, of any form or severity, of specifically designated persons or groups."
- Berger, Raoul. "Bills of Attainder: A Study of Amendment by the Court," 63 Cornell L. Rev. 355 (1977–78) outline
- Strasser, Mark. "Ex Post Facto Laws, Bills of Attainder, and the Definition of Punishment: On DOMA, the Hawaii Amendment, and Federal Constitutional Constraints," 48 Syracuse L. Rev. 227 (1998) outline DOMA is the Defense of Marriage Act
- Kenneth R. Thomas, Congressional Research Service. "The Proposed “Defund ACORN Act”: Is it a “Bill of Attainder?”"