This was a bill (first used apparently in 1321) passed by Parliament,
which might in itself decree sentence of death (SS351, 356).
Originally, the blood of a person held to be convicted of treason or
felony was declared to be *attainted* or corrupted so that his power
to inherit, transmit, or hold property was destroyed. After
Henry VIII's reign the law was modified so as not to work "corruption
of blood" in the case of new felonies. Under the Stuarts, Bills of
Attainder were generally brought only in cases where the Commons
believed that impeachment would fail,--as in the cases of Strafford
and Laud. It should be noticed that in an Impeachment the Commons
bring the accusation, and the Lords act as judges; but that in a Bill
of Attainder the Commons--that is, the accusers--themselves act as
judges, as well as the Lords.