Definition
Defectus sanguinis (Latin: "failure of blood" or "failure of issue") is a common law doctrine describing the extinction of a family line — the condition that arises when a person dies leaving no heirs of the blood capable of inheriting. In its most direct application, it refers to the failure or want of issue: the circumstance in which no lineal descendants or qualifying blood relations survive to take property by descent.
Under the feudal and common law of real property, land descended according to strict rules of blood. When the bloodline failed entirely — no issue, no collateral heirs within the recognized degree — the land escheated to the lord (or, later, to the Crown or state) for want of an heir. Defectus sanguinis was one of the recognized grounds triggering escheat, the other principal grounds being attainder (corruption of blood) and the alienage of the heir.
Common Confusion
Defectus sanguinis is sometimes loosely treated as synonymous with "failure of issue" or "want of heirs," but precision matters in historical research. Failure of issue is a broader concept that includes both the extinction of a line before a contingent limitation vests and the condition of dying without descendants capable of taking under a specific devise or entail. Defectus sanguinis specifically names the blood-failure ground for escheat or reversion — the state of the bloodline, not merely the outcome in a particular conveyance. Researchers working with fee tail and executory interest cases should keep the two concepts distinct.
Why It Matters in Research
The term appears almost exclusively in older common law materials — feudal tenure treatises, early English land law commentaries, and American cases decided before the broad statutory reforms of the nineteenth century that abolished fee tail and restructured descent. It is rarely encountered in modern American case law as a live doctrine.
For corpus researchers, the principal traps are:
First, the Rapalje & Lawrence entry for this term is garbled in the available source text — the definition runs into an unrelated passage about equity pleading (the "bill or not" language clearly belongs to a different entry). Treat Rapalje & Lawrence as unreliable for this term and do not build argument on it.
Second, because the term implicates escheat, researchers should trace parallel statutory developments carefully. American jurisdictions largely replaced the common law of escheat by statute, and those statutes use English rather than Latin phrasing. The term defectus sanguinis will appear in the cases that tested the pre-statutory common law but will drop out of the literature once legislatures codified escheat rules using vernacular terms.
Third, for research involving fee simple conditional, fee tail, and executory interests, defectus sanguinis connects directly to the rules governing when a contingent remainder or conditional fee would fail: if the required blood condition could never be satisfied because the line was extinguished, the interest might be treated as void or as having reverted. This doctrinal connection means the term can appear in property treatises under headings that do not obviously signal its presence — look in chapters on escheat, descent and distribution, and failure of condition.
Fourth, the term carries a constitutional dimension in American history only obliquely: the Constitution prohibits bills of attainder and limits corruption of blood as a consequence of treason, which effectively forecloses one of the other main escheat grounds. This makes defectus sanguinis (the natural failure of blood) the more durable common law basis, and it surfaces in some post-Revolutionary cases that needed to distinguish attainder-based forfeiture from natural-failure escheat.
Historical Dictionary Support
Black's Law Dictionary gives the cleanest definition: "failure of issue." That two-word gloss is accurate as far as it goes but strips away the feudal property context that gives the term its analytical weight. Black's entry is serviceable for identification but insufficient for application.
The Rapalje & Lawrence text provided is clearly defective — the entry begins to define the term and then continues into what is plainly material from an adjacent entry on equity pleading (demurrer, plea, and answer to a bill in equity). This is either a transcription error or a printing defect in the source. Neither the equity pleading material nor the truncated transition has any bearing on defectus sanguinis. Researchers should not rely on this source for the term.
What the historical dictionaries collectively miss is the connection between defectus sanguinis and the broader theory of tenure: land was held of a lord on conditions, and the blood of the tenant was the continuing link between the grant and its enjoyment. When that blood failed, the tenure could not continue and the land reverted or escheated. That structural explanation is absent from the terse dictionary entries and must be drawn from treatise sources such as Coke on Littleton or Blackstone's Commentaries, Book II.
Jurisdictional Note
Defectus sanguinis as a live doctrine belongs to English common law and to American jurisdictions that received that common law before statutory reform. Because fee tail was abolished by statute in most American states during the eighteenth and nineteenth centuries, and because modern escheat statutes have displaced the common law framework, the term has no active doctrinal role in contemporary American practice. It remains relevant for historical land title research and for understanding early American property cases.