A bill of attainder (also known as an act of attainder or writ of attainder or bill of penalties) is an act of a legislature declaring a person, or a group of people, guilty of some crime, and punishing them, often without a 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.
In the history of England, the word "attainder" refers to people who were declared "attainted", meaning that their civil rights were nullified: they could no longer own property or pass property to their family by will or testament. Attainted people would normally be punished by judicial execution, with the property left behind escheated to the Crown or lord rather than being inherited by family. The first use of a bill of attainder was in 1321 against Hugh le Despenser, 1st Earl of Winchester and his son Hugh Despenser the Younger, Earl of Gloucester, who were both attainted for supporting King Edward II. Bills of...