Definition
Princes of the blood are male members of a royal family who descend from a sovereign but stand outside the direct line of succession to the throne. In the British constitutional tradition, the term encompassed the younger sons of the reigning monarch and male members of collateral royal branches — those carrying royal lineage without holding the immediate expectation of the crown. The designation was not merely honorific; it carried legal consequences relating to titles, precedence, ceremonial duties, allowances from the Civil List, and restrictions on marriage and public conduct.
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Common Language
Modern common usage (Wiktionary): Members of a royal family who are closely related to the monarch, especially those of the male line.
Historical common usage (Webster's 1913): No distinct entry; "prince" was defined broadly as a sovereign ruler or the son of a king or emperor.
The gap between common and legal usage is meaningful. In ordinary speech, "prince" can refer loosely to any titled male member of a royal house or even a sovereign in his own right. As a legal category, princes of the blood had a defined constitutional and statutory position — their rights, obligations, and even their capacity to marry were regulated by instruments such as the Royal Marriages Act 1772 (UK). The common usage carries none of this legal freight.
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Common Confusion
Princes of the blood should not be confused with the heir apparent or heir presumptive, who occupy a distinct legal position as the designated successor to the throne. A prince of the blood may be a member of the royal family without being in direct line at all, or may occupy a distant position in that line. In French constitutional history, "princes du sang" carried a parallel but distinct meaning, referring to those legally recognized as royal descendants with specific rights to the succession under Salic law — a category that was formally enumerated and could be the subject of litigation. English and French usages are related but not interchangeable, and conflating them in historical sources can mislead researchers.
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Why It Matters in Research
This term appears almost exclusively in historical legal sources, constitutional law treatises, and materials touching the law of royal families, peerage, and British constitutional practice. Researchers should be aware of several navigational points.
First, the term is essentially obsolete as an operative legal category in modern British law. Research touching contemporary royal family law will encounter different frameworks — Letters Patent, the Succession to the Crown Act 2013, and related instruments — without the phrase appearing as a term of art.
Second, in historical corpus materials, the term bridges two distinct bodies of law: domestic constitutional law governing the British royal family, and the law of nations as applied to foreign sovereigns and their families. When encountered in treatises on international law or diplomatic law, "princes of the blood" may refer to French, Spanish, or other continental royal relatives, each governed by different succession rules. Bouvier's definition, shaped by the English constitutional tradition, should not be read as universally applicable.
Third, the legal significance of the category in English law was substantially shaped by statute. The Royal Marriages Act 1772 imposed restrictions specifically on descendants of George II (with narrow exceptions), and the category of persons subject to it overlaps heavily with what Bouvier calls princes of the blood. Researchers tracing individual cases — disputes over marriage validity, succession claims, or parliamentary grants — should move quickly from the dictionary term to the relevant statutory and Letters Patent framework.
Fourth, in American legal sources, the term has no operative domestic meaning but appears in treatises on the law of nations and in historical commentary on diplomatic privilege and the treatment of foreign royal visitors.
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Historical Dictionary Support
Bouvier's definition is accurate as far as it goes but notably compressed. It identifies the two core groups — younger sons of the sovereign and male members of collateral royal branches not in the direct line — without engaging the legal consequences that attach to membership in this category. Bouvier does not address the French "princes du sang," which had a more elaborate and litigated legal history, nor does he engage the question of how membership in the category was formally established or disputed.
What Bouvier's entry misses entirely is the procedural and statutory dimension: the category generated real legal disputes, particularly around marriage validity under the Royal Marriages Act 1772, claims to parliamentary grants, and questions of diplomatic immunity when foreign princes visited England. Historical legal dictionaries generally treat "princes of the blood" as a status term rather than as a source of justiciable rights and obligations, which understates the term's operational significance in the periods when it was actively used.
No other major historical dictionary in the Law Mind corpus provides a distinct entry for this term.
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Jurisdictional Note
The term carries operative historical meaning primarily in English constitutional law and, separately, in French constitutional and succession law. In the United States, it functions only as a term of historical or comparative reference. Researchers working in continental European legal history should not assume the English definition applies; French, Spanish, and other royal houses developed their own legally distinct categories of royal kinship with different succession implications.
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