Definition
Anatocismus is the charging of compound interest — that is, the practice of adding accrued interest to principal so that the accumulated interest itself begins to earn further interest. The term derives from Roman and civil law and describes a practice that was the subject of explicit legal regulation in the Justinianic corpus. In its narrowest civil-law sense, it refers specifically to the compounding of interest on interest already due, as distinguished from ordinary usury, which concerned the rate of interest charged on principal alone.
Common Confusion
Anatocismus is sometimes treated as a synonym for usury, but the two concepts are distinct. Usury concerns interest charged at an unlawful or excessive rate on a principal sum. Anatocismus concerns the structural mechanism of compounding — interest generating further interest — regardless of whether the underlying rate is lawful. A loan could be usurious without involving anatocismus (excessive simple interest) or could involve anatocismus without being usurious in the classical sense (lawful rate, but compounded). In modern legal discourse, the compound-interest prohibition derived from anatocismus doctrine has largely been absorbed into usury statutes and contract defenses, which can obscure the original conceptual distinction when researching historical sources.
Why It Matters in Research
Researchers encounter anatocismus most often in three contexts: civil law commentary, admiralty and maritime law, and historical usury doctrine.
In civil law research, the term appears in the Justinianic Code (Cod. 4.32–33) and in civilian treatises interpreting those provisions. The prohibition on anatocismus in Roman law was not absolute — maritime loans and certain commercial contexts admitted compound interest under specific conditions — so researchers should not assume a blanket prohibition when reading civilian sources.
In admiralty and maritime law, the connection is significant. Burrill's citation to Loccenius, De Jure Maritimo (lib. 2, c. 6, sect. 5), signals that compound interest in the context of maritime lending (foenus nauticum or bottomry) was treated differently from ordinary loan interest. Maritime risk justified departures from the general civilian rule against anatocismus. Researchers working on historical bottomry bonds or maritime interest disputes will need to track this exception carefully.
In common-law jurisdictions, the term itself rarely appears in case law or statutes — common-law courts addressed the same underlying problem through usury law and equitable doctrines governing penalties and unconscionable terms rather than through the civilian vocabulary. A researcher finding anatocismus in an American or English legal source is almost certainly reading a treatise writer drawing on civilian learning, not a court applying a recognized common-law doctrine by that name.
The practical trap: because modern compound-interest disputes are litigated entirely under statutory usury law, consumer protection regulations, or contract principles, researchers working backward from a modern issue to historical sources may fail to locate relevant civilian material if they search only for "compound interest" and miss the anatocismus entry in older dictionaries and treatises.
Historical Dictionary Support
Burrill's Law Dictionary provides the core entry and captures the essentials accurately: anatocismus is compound or "repeated, doubled" interest, rooted in the Greek and Latin civil-law tradition. Burrill's citation to Cod. 4.33.28 and 4.33.30 is reliable — those provisions of the Justinianic Code address the prohibition on interest upon interest in the context of ordinary loans. His citation to Loccenius correctly situates the maritime exception within the specialist literature on sea-law.
What Burrill does not address, and what researchers should note, is the nuance within Roman law itself: the prohibition on anatocismus applied primarily to annual compounding in private lending, while shorter-period compounding in commercial contexts had a more complicated status. Later civilian commentators debated the scope of the prohibition considerably. Burrill's entry, as is characteristic of his dictionary's method, gives the definition and its classical sources without working through the doctrinal disputes.
No other source dictionaries were submitted for this entry. Researchers needing deeper civilian analysis should consult Pothier's treatises on obligations and interest, and for the maritime dimension, Emerigon's Traité des Assurances and the commentary tradition on Grotius and Vinnius.
Jurisdictional Note
Anatocismus as a named legal concept belongs to civil law systems. In common-law jurisdictions, the substance of the doctrine — whether compound interest is enforceable and under what conditions — is governed by usury statutes, which vary significantly by state in the United States and have been substantially modified by federal preemption in the banking context. Researchers working in Louisiana or Quebec, or in comparative law contexts, will find the civilian vocabulary more directly operative.