bill of attainder | Definition

Doc's CJ Glossary by Adam J. McKee
Course: Introduction / Criminal Law

A bill of attainder is an unconstitutional type of legislative act that pronounces a person guilty of a crime.


A bill of attainder is a legislative act that declares a specific individual or group guilty of a crime without the benefit of a trial. The United States Constitution explicitly prohibits bills of attainder, as they are considered a violation of the separation of powers and the right to due process.

Bills of attainder were a common practice in England before the American Revolution, and the English monarchy often used them to punish political enemies. The founders of the United States were well aware of the dangers of bills of attainder, and they included provisions in the Constitution to ensure that such bills would not be passed by the United States Congress.

Article I, Section 9, Clause 3 of the Constitution states that “No Bill of Attainder or ex post facto Law shall be passed.” This means that Congress is prohibited from passing any law that declares a person guilty of a crime and imposes punishment without the benefit of a trial. This provision ensures that the judicial branch, rather than the legislative branch, is responsible for determining guilt and imposing punishment.

The prohibition on bills of attainder is grounded in the principles of due process and the separation of powers. Due process requires that individuals be given notice and an opportunity to be heard before they are deprived of life, liberty, or property. Bills of attainder violate this principle by depriving individuals of their rights without a fair trial. The separation of powers requires that each branch of government be independent and free from interference by the others. Bills of attainder violate this principle by allowing the legislative branch to usurp the powers of the judiciary.

Despite the constitutional prohibition on bills of attainder, there have been instances in which lawmakers have attempted to pass such bills. For example, during the McCarthy era of the 1950s, several members of Congress proposed bills of attainder that would have declared various individuals guilty of communist sympathies and imposed punishment without a trial. However, these bills were ultimately defeated as unconstitutional.

In addition to being unconstitutional, they are also considered to be contrary to the principles of justice and fairness. Declaring a person guilty without the benefit of a trial denies individuals the opportunity to defend themselves and challenge the evidence against them. They also allow lawmakers to act as judge and jury without being subject to the same legal standards as a court of law.


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Last Modified: 04/08/2023


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