Definition
A procurator in rem suam is a person who holds a power of attorney or agency authority that was granted not for the benefit of the principal, but for the agent's own benefit — typically because the subject matter of the agency has been assigned to the agent as their own property. The phrase translates literally as "attorney in his own affair" or "agent with respect to his own thing."
The concept arises most clearly in the assignment of debts or choses in action. When a creditor assigns a debt to another party but the legal right to sue remains technically in the assignor's name, the assignee is often given a power of attorney to collect the debt in the assignor's name. In that arrangement, the assignee is acting as procurator in rem suam — nominally an agent, but substantively the beneficial owner. The agency is a legal mechanism, not a true representation of another's interests.
The practical consequence is significant: because the "principal" has no remaining interest in the matter, the ordinary rules of agency do not apply in the usual way. The principal cannot revoke the authority, because revocation would defeat the assignee's own property right. The agency is said to be coupled with an interest and is therefore irrevocable.
Common Confusion
Procurator in rem suam is sometimes loosely treated as synonymous with "agent" or "attorney-in-fact," but the distinction is material. An ordinary agent acts for the benefit of the principal and the principal may revoke the authority at will. A procurator in rem suam acts for their own benefit; the power is irrevocable because it exists to protect the agent's property interest, not to serve the principal. Conflating the two can lead to serious errors when analyzing whether a power of attorney survives the principal's attempt at revocation or death.
Why It Matters in Research
This term appears almost exclusively in older materials — Scots law treatises, equity cases, and pre-twentieth-century common law discussions of assignment. Researchers working in historical sources on debt assignment, negotiable instruments, or the development of chose-in-action transferability will encounter it as a doctrinal anchor.
Three research traps to watch:
First, the term is Scots law in origin and the historical sources reflect that lineage. Bouvier draws directly from Stair and Erskine, both foundational texts of Scots private law. When the term appears in English or American common law sources, it is usually borrowed from equity or Scots practice, and the doctrinal weight it carries may differ from jurisdiction to jurisdiction.
Second, modern legal writing has largely replaced this term with "irrevocable power of attorney coupled with an interest" or simply "power coupled with an interest." Researchers searching corpus materials for the underlying doctrine should run searches on both the Latin phrase and its modern English equivalents, or they will miss a large body of relevant material on each end of the chronological range.
Third, the connection to assignment of choses in action is historically important. At common law, assignment of a bare debt was not enforceable at law (though equity would protect it), and the mechanism of the procurator in rem suam — giving the assignee a power to sue in the assignor's name — was a workaround for this limitation. Understanding the term illuminates the doctrinal history of assignment law and why certain equity fictions were necessary before statutory reforms permitted legal assignment directly.
Historical Dictionary Support
Black's and Bouvier's entries are brief but complementary. Black's supplies the clean translation — "proctor in his own affair, or with reference to his own property" — without extended analysis. Bouvier's is more useful: it explains the assignment mechanism explicitly and cites Scots institutional writers (Stair's Institutions, Erskine's Institutes, and Bell's Dictionary), giving the term its proper doctrinal home in Scots private law.
Both sources treat the term as well-settled, which is accurate for the period in which they wrote. Neither anticipates that the underlying doctrine would be substantially absorbed into modern statutory assignment law or that the Latin phrase itself would fall into disuse. Researchers should not assume that the absence of the term in twentieth-century materials means the doctrine disappeared — it survived under different vocabulary.
Bouvier's adjacent entry on procuratorium (the instrument by which a proctor is appointed) is worth reviewing alongside this term for researchers examining the formal mechanics of historical powers of attorney.
Jurisdictional Note
The term is Scots law in origin and most precisely applicable there. In English and American equity practice, the same concept was recognized — an irrevocable power coupled with an interest — but the Latin phrase was used inconsistently and was never a term of art in the same way. American courts and treatises occasionally adopted it by reference to Scots or English equity sources, but researchers should not assume uniform usage or doctrinal equivalence across jurisdictions without verifying the specific court's frame of reference.