Definition
De asstimato (also rendered as de aestimato) is a Roman law contract belonging to the category of innominate contracts. Under this arrangement, property — land or goods — was transferred to a third party at a fixed, agreed-upon price (the aestimatio), with that third party undertaking to either sell the property to a purchaser and remit the agreed price, or return the property if a sale could not be achieved. The party who received the goods effectively guaranteed the fixed valuation.
As an innominate contract, de asstimato did not fall within the named, formally recognized contract types of Roman law (sale, hire, loan, mandate). Instead, it was one of four unnamed contract forms enforced under the principle that an obligation arises when one party has performed and the other has not — classified under the formula do ut des (I give so that you may give) or do ut facias (I give so that you may do). The de asstimato fits most naturally within this framework as a hybrid between sale and mandate, sharing features of each without being reducible to either.
In practical terms, the arrangement resembles what modern commercial law might recognize as a consignment with a guaranteed floor price, or a form of agency sale with price protection. The guarantor or recipient bore the risk that the market would not meet the aestimatio value; if no buyer materialized, the property could be returned, but the fixed price itself was the benchmark obligation.
Common Confusion
De asstimato is sometimes loosely described as a form of sale (emptio venditio), but Roman jurists distinguished the two carefully. In emptio venditio, a buyer acquires property and bears the price risk outright. In de asstimato, the recipient does not become a buyer in the full Roman sense — the obligation is conditional on finding a purchaser, and the property may revert. The arrangement is also distinct from mandatum (agency or commission), though it shares the feature of acting on another's behalf; unlike pure mandate, de asstimato involved the recipient taking physical possession and bearing financial exposure at a fixed valuation.
Why It Matters in Research
Researchers will encounter de asstimato almost exclusively in sources dealing with Roman private law or the civil law tradition, particularly in treatments of innominate contracts. Because the term does not map onto any single modern common law category, it requires careful contextual reading — historical sources that use the term may be explaining Roman contract doctrine, tracing the roots of consignment or agency law, or illustrating how civil law systems handled commercial arrangements that fell outside formal contract types.
The spelling varies across historical sources. Black's Supplemental renders it de asstimato, while the classical Latin form is de aestimato or aestimatio. Researchers using corpus search tools should run variants of both spellings to capture all relevant appearances.
The term will not appear in common law case reporters, and its relevance to modern American or English legal research is almost entirely historical and comparative. When it appears in a 19th- or early 20th-century legal text, the surrounding context typically involves either a historical survey of contract law origins or a comparison between civil law and common law approaches to agency, consignment, or price-guarantee arrangements.
Historical Dictionary Support
Black's Law Dictionary (2nd Ed., Supplemental) provides the only dictionary source here, and its entry is brief but accurate in its essentials: de asstimato is identified as an innominate Roman contract involving a fixed price (aestimato) and a third-party guarantor who undertook to find a purchaser. The entry correctly situates the term within the innominate contract category, which is the critical doctrinal anchor.
What Black's does not supply — and what researchers using this term will want — is the fuller Roman law framework. The innominate contracts were a late development in Roman jurisprudence, given actio praescriptis verbis to enforce them after one party had performed. The classical jurists, including discussion preserved in Justinian's Digest, treated the aestimatum (the underlying concept) as a recognized commercial practice warranting legal protection even without a formal nomen. Historical sources dealing with the Digest or the Institutes will provide richer treatment than any common law dictionary entry.