Definition
Addictio in diem (Roman and civil law) is a conditional sale agreement in which the seller reserves the right to rescind the transaction if, within a specified period, a better offer is received from another buyer. Under this arrangement, the initial sale is provisionally binding but subject to defeasance: if the seller obtains a more advantageous offer before the agreed deadline, the first contract is dissolved and the seller may accept the superior bid. If no better offer materializes within the time limit, the original sale becomes final and unconditional.
The term translates roughly as "adjudication for a day" or "sale subject to a day," reflecting the fixed time window within which the seller's right of rescission must be exercised. The device was not a mere option held by the seller at will; it required that a genuinely superior offer be presented within the contractually defined period. Absent that condition, the seller could not unilaterally withdraw.
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Common Confusion
Addictio in diem is sometimes confused with the in diem addictio discussed in the context of Roman slavery and judicial assignment, where addictio denoted a magistrate's formal award or assignment of a person. These are distinct institutions sharing a root. The commercial addictio in diem belongs exclusively to the law of sale; researchers encountering addictio in sources dealing with persons, status, or judicial proceedings are dealing with a different concept entirely.
Researchers should also distinguish addictio in diem from the lex commissoria, another Roman conditional-sale clause. Under the lex commissoria, the seller could rescind if the buyer failed to pay the price on time — a seller's remedy for non-payment. Addictio in diem, by contrast, operates as a seller's reservation to seek a better price, not as a remedy for default. Both clauses appear in Digest Book 18 and are easily conflated in historical sources.
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Why It Matters in Research
This term appears almost exclusively in civil law and Roman law sources. Researchers working in common law jurisdictions will encounter it only in historical comparative works, treatises on the civil law foundations of Louisiana, Quebec, or Scottish private law, or in scholarly discussions of Roman contract theory. It has no direct common law analogue and does not map neatly onto modern Anglo-American concepts like a right of first refusal or an option to purchase, though those terms may appear in secondary literature as rough translations.
The key research trap is anachronism: modern commercial law equivalents (auction reserve clauses, bump clauses in real estate contracts, matching-right provisions) share functional similarities with addictio in diem but differ in structure, enforceability mechanics, and the rights they create. Do not assume that a historical discussion of addictio in diem is applicable to disputes governed by modern contract or commercial law without tracing the jurisdictional lineage carefully.
For Louisiana and other mixed civil law jurisdictions, addictio in diem may appear in older treatises and pleadings as a recognized doctrinal category. Its practical relevance in those systems today depends on how the relevant civil code provisions on conditional sales and resolutory conditions have been interpreted by local courts and commentators.
The Digest reference in Burrill (Dig. 18) points to the title De contrahenda emptione in the Digest of Justinian, which remains the primary primary source. Researchers needing more than Burrill's summary should go directly to Digest 18.2, which addresses the lex commissoria, and 18.4, along with Pothier's Traité du contrat de vente, which elaborated these Roman sale conditions for the French and Louisiana civilian traditions.
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Historical Dictionary Support
Burrill's Law Dictionary provides the only entry among the shelf sources. His definition is compact but accurate: a sale with a clause allowing rescission if a more advantageous offer is found within a contractually fixed time. Burrill's citation to Digest 18 is correct in direction, though a more precise pinpoint would fall within the subtitles addressing sale conditions.
No entry appears in Black's, Bouvier's, or other common law-oriented dictionaries in the standard shelf, which reflects the term's civil law provenance and its limited penetration into Anglo-American legal writing. This absence is itself informative: the concept was not absorbed into English equity or common law doctrine, and researchers should not expect to find it treated in common law case reporters or standard Anglo-American treatises.
The historical sources do not address the question of whether addictio in diem operated as a condition precedent or condition subsequent to the sale — a distinction that would matter significantly under modern contract analysis. Civil law commentators have generally treated it as a resolutory condition: the sale is complete unless and until the rescission right is validly exercised.
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Jurisdictional Note
Addictio in diem is a civilian concept with no recognized common law counterpart. It may carry doctrinal weight in Louisiana, Quebec, and other mixed or civil law jurisdictions where Roman-derived sale law was codified. Researchers working in purely common law systems will encounter it only in historical or comparative contexts.
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Encyclopedia Cross-Reference
The matched encyclopedia entry (Damages and Remedies in Tort — Per Diem and Unit-of-Time Arguments) shares only the Latin in diem fragment and is not substantively related to addictio in diem. No Law Mind Encyclopedia entry directly addresses Roman sale law or civil law conditional contracts. Omitted as not relevant.
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