The History Learning Site states that a bill of attainder was legislation that declared someone guilty of a specific crime without a trial. For example, in 1542, Catherine Howard was executed via a bill of attainder for cheating on her royal husband Henry VIII.
The History Learning Site also states that the bill of attainder was once part of English common law. The bill of attainder had the ability to bypass the principle of habeus corpus, which requires a trial by jury.
According to the History Learning Site, the word attainder meant "tainted", which is fitting since the bill of attainder was most often used to punish those who were thought to be guilty of treason. Those guilty of treason were often executed shortly after the bill of attainder came into play, and their property then became the government's, since the guilty party did not have the privilege of a will.
The use of the bill of attainder began in the year 1321 and it was last used in 1798, according to the History Learning Site. Thomas Cromwell and Catherine Howard were the most famous victims of the bill of attainder. The bill of attainder was often used by English royalty in order to stop nobles who were "getting above themselves," states the History Learning Site. The last bill of attainder was written in 1798, and they were abolished in the United Kingdom in 1870.