"A bill of attainder (also known as an act of attainder or writ of attainder) is an act of a legislature declaring a person or group of persons guilty of some crime and punishing them without privilege of a judicial trial. As with attainder resulting from the normal judicial process, the effect of such a bill is to nullify the targeted person’s civil rights, most notably the right to own property (and thus pass it on to heirs), the right to a title of nobility, and, in at least the original usage, the right to life itself. Bills of attainder were used in England between about 1300 and 1800 and resulted in the executions of a number of notable historical figures. However, the use of these bills eventually fell into disfavour due to the obvious potential for abuse and the violation of several legal principles, most importantly separation of powers, the right to due process, and the precept that a law should address a particular form of behavior rather than a specific individual or group. For these reasons, bills of attainder are expressly banned by the United States Constitution as well as the constitutions of all 50 US states."
U.S. usage
Bills of attainder were used through the 18th century in England, and were applied to British colonies as well. One of the motivations for the American Revolution was anger at the injustice of attainder. Although at least one American state used a bill of attainder to confiscate the property of a British loyalist (called Tories) during the war (New York, in the 1779 case of Parker Wickham), American dissatisfaction with British attainder laws motivated their prohibition in the U.S. Constitution ratified in 1789.
Excerpt from Article One, Section 9 of the United States Constitution, prohibiting the passing of bills of attainderThe United States Constitution forbids legislative bills of attainder under Article I, Section 9. The provision forbidding state law bills of attainder, Article I, Section 10, reflects the importance that the framers attached to this issue.
Within the U.S. Constitution, the clauses forbidding attainder laws serve two purposes. First, they reinforced the separation of powers, by forbidding the legislature to perform judicial or executive functions—since the outcome of any such acts of legislature would of necessity take the form of a bill of attainder. Second, they embody the concept of due process, which was partially reinforced by the Fifth Amendment to the Constitution. The text of the Constitution, Article I, Section 9; Clause 3 is "No Bill of Attainder or ex post facto Law shall be passed".
The constitution of every State also expressly forbids bills of attainder. For example, Wisconsin's constitution Article I, Section 12 reads:
"No bill of attainder, ex post facto law, nor any law impairing the obligation of contracts, shall ever be passed, and no conviction shall work corruption of blood or forfeiture of estate."
Contrast this with the subtly more modern variation of the Texas version: Article 1 (Titled Bill of Rights) Section 16, entitled Bills of Attainder; Ex Post Facto or Retroactive Laws: Impairing Obligation of Contracts:
"No bill of attainder, ex post facto law, retroactive law, or any law impairing the obligation of contracts, shall be made".