Definition
An act of attainder is a legislative enactment that directly declares a named individual (or identifiable group) guilty of a crime — typically treason or felony — and imposes punishment, including death, forfeiture of property, and civil disabilities, without trial by a court of law. The legislature acts as judge, jury, and sentencer simultaneously. The result of such an act was attainder: the corruption of the condemned person's blood, meaning their heirs could neither inherit from them nor transmit property through them.
In Anglo-American legal history, acts of attainder were instruments of political persecution. English and colonial legislatures used them to destroy political enemies when conviction through ordinary judicial process was uncertain or inconvenient. The United States Constitution expressly prohibits Congress and the states from passing bills of attainder — the prospective form of the same instrument — making the act of attainder not merely obsolete in American law but affirmatively unconstitutional.
The term "act of attainder" typically refers to a completed legislative punishment of a specific, identified person, often one already dead or in exile, as distinguished from a "bill of attainder," which historically referred to acts carrying the death penalty as opposed to bills of pains and penalties, which imposed lesser punishments. American constitutional doctrine has collapsed this distinction, treating all three as prohibited bills of attainder.
Common Confusion
ACT OF ATTAINDER vs. BILL OF ATTAINDER vs. BILL OF PAINS AND PENALTIES: At English common law, these were formally distinct. A bill of attainder imposed death. A bill of pains and penalties imposed lesser punishments — imprisonment, banishment, forfeiture — without the full consequences of attainder. An act of attainder was essentially a bill of attainder that had been enacted into law. American constitutional usage, confirmed by the Supreme Court, treats all three as constitutionally equivalent "bills of attainder" prohibited by Article I, Sections 9 and 10. Researchers working in English legal sources before the nineteenth century must respect the original distinctions; researchers working in American constitutional law need not.
Why It Matters in Research
This term sits at the intersection of constitutional law and English legal history, and the research path differs sharply depending on which side of the Atlantic — and which century — you are investigating.
In English sources, acts of attainder appear throughout Parliamentary records from the medieval period through the eighteenth century. Researchers working with those sources will encounter the term in its precise historical sense, where the formal distinctions between acts of attainder, bills of attainder, and bills of pains and penalties carry real legal weight. The consequences of attainder — corruption of blood, forfeiture, civil death — are distinct legal outcomes that shaped inheritance law and property records. Missing these distinctions will produce misreadings.
In American sources, the constitutional prohibition swallowed the historical taxonomy. American courts and commentators use "bill of attainder" as the generic term for all legislative punishment, and the act/bill distinction carries no operative legal significance. The relevant constitutional question is functional: did the legislature impose punishment on a specific individual or identifiable group without judicial trial? Searching American case law for "act of attainder" will return far fewer results than searching "bill of attainder"; researchers should use both.
A significant trap in historical American sources (colonial period through early republic) is that "act of attainder" appears in its English sense. Several American states passed acts of attainder against Loyalists during and after the Revolutionary War — these are genuine attainders with forfeiture consequences that affected land records and inheritance for generations. Researchers tracing property titles or estate histories from that period may encounter downstream effects of these legislative acts without recognizing their origin.
The corruption of blood doctrine, though formally abolished in England by statute in the nineteenth century and barred in the United States by Article III, Section 3 of the Constitution, generated substantial historical litigation. Corpus searches for "act of attainder" in early American legal materials should be cross-referenced against forfeiture records and land grant disputes.
Historical Dictionary Support
Black's Law Dictionary treats the act of attainder as a legislative act attainting a person and directs readers to the substantive entry on attainder — a lean cross-reference that correctly signals where the real doctrine lives. This is representative of how legal dictionaries handle the term: it functions primarily as a pointer to attainder and bill of attainder rather than as a standalone doctrinal category. Historical legal dictionaries generally agree on the core meaning. Where they diverge is in how carefully they maintain the act/bill/pains-and-penalties distinctions, which loosened considerably in American usage after the constitutional prohibition made the distinctions practically irrelevant.
What historical sources often miss or compress is the procedural mechanics of attainder proceedings — how they operated in Parliament, what procedural protections (if any) applied, and how they interacted with common law courts. Researchers needing that level of detail should look beyond dictionary sources to Coke's Institutes and Blackstone's Commentaries, both of which address the subject in depth.
Jurisdictional Note
Constitutionally prohibited in the United States at both federal and state levels. Abolished in England as a practical instrument by the nineteenth century. Researchers working in Scottish, Irish, or colonial legal records should be alert to jurisdictional variants in how attainder was implemented and its consequences assessed.