Definition
"Peto" is a Latin legal term with two distinct historical meanings depending on the legal tradition in which it appears.
1. Roman Law — I request. In Roman law, peto was a standard testamentary word used to create a fideicommissum, or trust. A testator writing "peto" in a will was understood to be making a request to an heir or legatee to hold property for the benefit of a third party. The word's precatory character distinguished the fideicommissum from a direct legacy — it was framed as an appeal to the conscience of the recipient rather than a binding command — though Roman law ultimately made fideicommissa legally enforceable. The Institutes of Justinian (2.24.3) identify peto as one of the recognized words capable of creating this obligation.
2. Old English Law — I demand. In early English common law pleading, peto was the opening word of a demandant's count in a real action. A party bringing a claim to land would begin the count with peto, stating in first-person form what land was being demanded and on what ground — for example, demanding dower from a named party over specified land in a named town. The word signaled a formal claim of right in proceedings before the royal courts.
Common Language
Modern common usage (Wiktionary): A surname; also a municipality in Yucatán, Mexico. No legal meaning in contemporary English.
Historical common usage (Webster's 1913): Not independently defined; "peto" does not appear as an English word in Webster's 1913.
The gap here is not between legal and common usage but between the term's two legal usages across different legal systems. In neither Roman nor English law does peto carry meaning that resembles its modern nominal uses. Researchers encountering the word in historical legal text should first identify the jurisdiction before interpreting the term.
Common Confusion
The precatory character of peto in Roman law occasionally leads to confusion about the enforceability of fideicommissa. Because peto means "I request" rather than "I direct" or "I command," modern readers sometimes assume the obligation was unenforceable — a moral appeal only. This was historically true in the early Republic, but by the classical period Roman law had fully incorporated fideicommissa into enforceable obligations. The word's soft register does not reflect its legal force in the Justinianic sources where it most commonly appears.
In the English pleading context, peto should not be confused with the Latin petitio (a petition or formal claim), though the two words share the same root. Peto as the first-person singular verb form was the specific formulaic opener of the demandant's count; petitio referred more broadly to the claim or prayer for relief as a noun.
Why It Matters in Research
Researchers working in Roman law sources — particularly in the Digest and the Institutes — will encounter peto as part of the formulaic vocabulary of testamentary drafting. The Institutes passage cited in all three source dictionaries (Inst. 2.24.3) is the anchor reference: it lists the words capable of creating a fideicommissum, and peto is among them. Any research into the history of trusts, equitable obligations, or testamentary practice in civil law systems should treat this passage as foundational.
In English legal sources, peto appears primarily in the plea rolls and in treatises on real actions — Bracton and Fleta being the key texts. Because real actions were largely abolished in England by the early nineteenth century, peto in the English pleading sense is a term of purely historical interest. Researchers tracing the vocabulary of early English land litigation, dower claims, or the structure of the medieval count will encounter it in Bracton (fol. 313b) and Fleta (lib. 5, c. 32, § 3; lib. 6). These are the sources to consult; the word will not appear in modern English pleading forms.
The dual meaning is the primary trap. A researcher moving between Roman law materials and English common law materials without recognizing the jurisdictional shift may misread the term's function. In Roman sources, peto signals a trust creation; in English sources, it signals a demand for land.
Historical Dictionary Support
All three source dictionaries agree on the Roman law definition: peto means "I request" and is a recognized word for creating a fideicommissum, citing Inst. 2.24.3. Black's first and second editions are substantially identical on this point and add nothing beyond the citation.
Burrill's Law Dictionary is the more complete source. It adds the English pleading usage — absent entirely from both editions of Black's — citing Bracton and Fleta for the proposition that the demandant's count in old English real actions opened with peto. This is the entry's most historically distinctive contribution. Researchers relying solely on Black's will miss the English common law dimension of the term.
No source addresses the enforceability arc of the fideicommissum or the eventual codification of trust obligations in Roman law — context that researchers will need to supply from external sources such as the Digest or secondary scholarship on Roman testamentary law.
Jurisdictional Note
In Roman law (and its civil law descendants), peto carries meaning within the law of testamentary trusts and fideicommissa. In early English common law, its function was confined to the formulaic structure of real actions, which no longer exist as a procedural category. The term has no operative legal meaning in any modern common law or civil law jurisdiction; its relevance is exclusively historical.
Encyclopedia Cross-Reference
Law Mind Encyclopedia — Fideicommissum (for the Roman law trust context and the enforceability of precatory testamentary language)
Law Mind Encyclopedia — Dower (for the English real action context, where peto appeared in dower claims specifically)