Definition
Cosinage refers to two related but distinct concepts in the old common law:
1. Consanguinity — the relationship of persons descended from a common ancestor; kinship by blood. In this sense, cosinage denotes collateral blood relationship generally, without specifying the degree of proximity.
2. A writ of cosinage (also called the writ of cosinage) — a real action available at common law to recover possession of lands when a stranger had entered following the death of a remote collateral ancestor, typically the grandfather's grandfather or another ancestor beyond the degree covered by the more immediate writs of aiel and besaiel. The writ was one of a series of possessory remedies designed to address successively more remote descents.
Common Language
Modern common usage (Wiktionary): Collateral relationship or kindred by blood; consanguinity. Also, the writ to recover land after entry by a stranger following the death of a remote collateral ancestor.
Historical common usage (Webster's 1913): Collateral relationship or kindred by blood; consanguinity. Also, a writ to recover possession of an estate in lands when a stranger has entered after the death of the grandfather's grandfather or other distant collateral relation.
The overlap between common and legal meaning is unusually close here because both usages descend from the same archaic legal tradition. The gap worth noting is subtle but real: in ordinary historical usage, cosinage meant simply blood kinship; in legal usage, the term also named a specific procedural writ with precise technical requirements tied to degree of descent. A reader encountering the word in an old text must determine from context whether the author means the relationship itself or the writ that invoked it.
Recognized Forms
/SUBTYPES
The writ of cosinage was part of a graduated series of real actions distinguished by the remoteness of the ancestor through whose death the plaintiff traced a claim:
- Writ of novel disseisin: addressed disseisin of the claimant directly.
- Writ of mort d'ancestor: addressed entry after the death of an immediate ancestor (father, mother, brother, sister, uncle, aunt).
- Writ of aiel: addressed entry after the death of a grandfather or grandmother.
- Writ of besaiel: addressed entry after the death of a great-grandfather or great-grandmother.
- Writ of cosinage (tresaiel in some formulations): addressed entry after the death of any more remote collateral ancestor beyond these degrees.
These distinctions were procedurally significant; choosing the wrong writ could be fatal to the action.
Why It Matters in Research
Cosinage is an obsolete term of purely historical significance. No modern jurisdiction employs the writ; it was effectively superseded in England by the Real Property Limitation Act 1833 and equivalent reforms, and was never meaningfully transplanted into American practice. Researchers are most likely to encounter it in:
- Digests and treatises on common law real actions (Blackstone's Commentaries, Fitzherbert's Natura Brevium, early English Year Books).
- Historical land dispute records from medieval and early modern England.
- Comparative common law scholarship discussing the evolution from possessory writs to modern ejectment.
The primary research trap is confusing the two senses of the word. When cosinage appears in a genealogical or probate context, it likely means consanguinity. When it appears in a procedural or pleading context — particularly alongside aiel or besaiel — it refers to the writ. Rapalje & Lawrence use both senses without fully separating them, which can mislead a researcher who reads the entry quickly.
A secondary trap: the writ of cosinage was of "general application" in the sense that it swept up all ancestral degrees not covered by the more specific writs — it was not general in the modern sense of broadly available. The phrase in Rapalje & Lawrence signals breadth of ancestral coverage, not ease of use or wide availability.
Historical Dictionary Support
Rapalje & Lawrence identify cosinage as meaning consanguinity and note the writ, but treat the entry briefly. Webster's 1913 and Wiktionary — both drawing on Blackstone and Burrill — are more precise about the writ's mechanics, specifying the grandfather's grandfather as the triggering ancestor. Blackstone's account in the Commentaries remains the most accessible treatment of the graduated writ system in which cosinage appears.
None of the available historical dictionary sources fully explains why the series of writs was necessary or how the system collapsed. That context must be sought in common law history sources rather than dictionary entries. Historical dictionaries are consistent on the core definition but silent on practical usage, which reflects how thoroughly obsolete the term had become even by the time these dictionaries were compiled.
Jurisdictional Note
The writ of cosinage was an English common law remedy and was never adopted as a functioning procedural tool in American courts. American jurisdictions moved directly toward ejectment as the primary real action. The term may appear in early American legal writing as a reference to English authority, but carries no operative American procedural content.