Definition
In law, "blood" does not refer to the biological fluid but to the legal concept of kinship by descent — the relationship that connects persons through a common ancestor, enabling certain legal consequences to flow between them. The term operates primarily in two contexts:
1. CONSANGUINITY AND FAMILY RELATIONSHIP. "Blood" denotes the tie of natural descent, whether lineal (parent to child) or collateral (siblings, cousins). A person is said to be "of the blood" of another when a traceable genealogical line connects them through shared ancestry. This usage appears throughout property, inheritance, and family law.
2. BLOOD AS A QUALIFYING CHARACTERISTIC FOR INHERITANCE. Historically, "blood" was the quality or legal status that entitled a person to take property by descent. A claimant had to be "of the blood" of the ancestor through whom property descended; an heir who lacked that blood — such as a spouse or a person related only by marriage — was disqualified from inheriting at common law. This is sometimes called "blood inheritable" in the older authorities.
WHOLE BLOOD AND HALF BLOOD. Brothers and sisters are of the whole blood when they share both the same father and the same mother. They are of the half blood when they share only one parent in common. At early common law, half-blood relatives were excluded from inheritance in many circumstances; American law has generally abolished or limited this distinction.
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Common Language
Modern common usage (Wiktionary): "Blood" is a vital liquid flowing in the bodies of many animals, conveying nutrients and oxygen; informally, a family relationship due to birth, contrasted with relationships arising from marriage or adoption.
Historical common usage (Webster's 1913): "The fluid which circulates in the principal vascular system of animals"; also, "relationship by descent from a common ancestor; consanguinity; kinship."
Editorial note: The biological sense of blood is irrelevant to legal usage. Even in the secondary, relational sense shared by ordinary English and legal English, the legal term carries a sharper, more technical edge: it specifies a quality of relationship that historically governed whether a person could take property by descent at all, not merely whether two people are "family." The legal meaning of blood can determine inheritance rights, disqualify claimants, and structure the entire architecture of intestate succession — functions that the casual familial sense does not carry.
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Common Confusion
BLOOD vs. KINDRED. These terms overlap but are not identical. Kindred is the broader category: it encompasses all persons related to a decedent, potentially including those related by affinity in certain historical usages. Blood in the strict legal sense excludes relationships by marriage or adoption and focuses on natural, consanguineous descent. In intestate succession analysis, the distinction matters: not all kindred are "of the blood" for purposes of inheriting real property descended from a particular ancestor.
WHOLE BLOOD vs. HALF BLOOD. Researchers frequently encounter both terms in succession statutes and cases without recognizing that the legal consequences attached to each shifted dramatically between the common law period and modern American statutory law. At common law, half-blood relatives could be excluded from inheritance entirely. Most American jurisdictions now treat half-blood and whole blood relatives equally or nearly so in intestate succession, though some states retain modified distinctions. Reading a historical source without knowing which rule was in force produces serious errors.
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Core Elements
For "blood" to qualify a claimant as an heir entitled to take by descent at common law, the following were required:
1. NATURAL DESCENT. The relationship must arise from biological parentage, not from legal acts such as marriage or adoption. Stepchildren and in-laws are not "of the blood" for this purpose.
2. TRACEABLE LINE TO THE COMMON ANCESTOR. The claimant must be able to trace a genealogical connection to the specific ancestor through whom the property descended, not merely to the decedent generally.
3. INHERITABLE BLOOD. Early common law required that the claimant's blood not be "attainted" — corruption of blood, a consequence of conviction for treason or felony, could bar a person and their descendants from inheriting. American constitutional law abolished attainder of blood for federal purposes; most states followed.
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Recognized Forms
/SUBTYPES
WHOLE BLOOD. Relationship through both the same father and the same mother.
HALF BLOOD. Relationship through one common parent only.
BLOOD INHERITABLE. The historical term for the quality of legal capacity to take by descent — blood that has not been corrupted by attainder or other legal disqualification.
CORRUPTION OF BLOOD. The consequence at common law of a bill of attainder or conviction for treason: the person's blood was deemed "corrupted," barring them and their lineal descendants from inheriting or transmitting property by descent. Prohibited under Article III of the U.S. Constitution as a consequence of attainder of treason.
BLOOD RELATIVE. A person connected by consanguinity, as distinguished from a person related by marriage (affinity) or legal act (adoption).
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Why It Matters in Research
Historical inheritance law was built on the concept of blood, and the Law Mind corpus reflects this across centuries of property, probate, and family law materials. Researchers need to track several fault lines:
HALF-BLOOD RULES SHIFT DRAMATICALLY. Cases and statutes from the eighteenth and early nineteenth centuries may reflect the common law rule excluding half-blood heirs from real property descent entirely, or relegating them to a subordinate position. Later American statutes progressively equalized whole and half blood. A case interpreting an intestacy statute from 1820 may produce a result exactly opposite to what would follow under a modern statute. Always identify which version of the rule was in force.
CORRUPTION OF BLOOD AS A RESEARCH TRAP. Treatises and cases from the colonial and early republic period discuss corruption of blood as an operative legal concept. The U.S. Constitution bars Congress from working corruption of blood as a punishment for treason, and most state constitutions contain analogous provisions. However, references to "attainder" and "corruption of blood" persist in historical texts even after those doctrines had been constitutionally abrogated. Researchers should not assume a historical source describes still-viable law.
BLOOD AND REAL PROPERTY DESCENT. The ancient common law rule required that an heir be "of the blood of the first purchaser" — the person who originally acquired the land. This rule of ancestral property limited descent of real estate in ways that have no modern counterpart. Sources discussing descent of real property before the mid-nineteenth century may invoke this principle, which was abolished by statute in most American states.
ADOPTION AND BLOOD. Because "blood" in the legal sense traditionally meant natural consanguinity, adopted children historically were not "of the blood" of their adoptive family for inheritance purposes. Many states have amended their statutes to treat adopted children as blood relatives for all or most intestacy purposes, but historical cases and some surviving statutory language still reflect the older exclusion.
CORPUS CONNECTIONS. The term "blood" as a legal concept appears throughout Law Mind materials on intestate succession, real property descent, attainder, adoption, and parentage. Cross-referencing entries on CONSANGUINITY, DESCENT, HEIR, HALF BLOOD, and CORRUPTION OF BLOOD is essential when working with historical inheritance sources.
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Historical Dictionary Support
The major historical dictionaries converge on the core definition: blood means kindred, consanguinity, and the relationship of natural descent from a common ancestor. Black's (both editions), Bouvier's, Burrill's, and Anderson's are consistent on this point, each tracking the formula that a person is "of the blood" of another when connected by lineal or collateral descent.
Rapalje and Lawrence offer the most analytically useful formulation by separating the two legal functions of the term: (1) the quality enabling a person to take by descent — "blood inheritable" — and (2) the collective body of persons so related. This distinction is genuinely useful and not always made explicit in the other dictionaries.
Burrill adds a point of particular importance for American researchers: "In American law, blood includes the half blood as well as the whole blood," citing 2 Peters' R. 5. This divergence from the English common law rule is significant, and Burrill's explicit flagging of it is a research aid. Bouvier and Black do not emphasize this American departure as clearly.
None of the historical dictionaries give sustained attention to the constitutional abrogation of corruption of blood, though the concept is mentioned in passing. Researchers relying solely on historical dictionary definitions will miss the constitutional overlay that renders attainder and corruption of blood largely defunct as operative doctrines in American law while still present as interpretive background in historical sources.
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Jurisdictional Note
American states have largely equalized whole-blood and half-blood heirs in intestate succession, but not uniformly. A minority of states retain some distinction, typically giving half-blood relatives a smaller share than whole-blood relatives when both classes compete. The rule governing descent of ancestral or ancestral real property — requiring that an heir be "of the blood of the first purchaser" — was abolished by statute at different times across jurisdictions, and its traces appear in varying degrees in state case law through the nineteenth century.
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Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Intestate Succession; Descent and Distribution; Corruption of Blood and Attainder; Consanguinity and Affinity.
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