Definition
Ley is an Old French term, a corruption of loi, meaning "law." It appears in two distinct senses in historical English legal materials.
1. Law generally. In this sense, ley functions as a direct equivalent of the Latin lex or the English "law," appearing most often in the titles or phrases of legal texts — most famously in Termes de la Ley, the influential glossary of English legal terms compiled in the late medieval period. Here the word carries no technical freight beyond its literal meaning.
2. Oath or wager of law (the older technical sense). In earlier medieval usage, ley also denoted a sworn oath, and more specifically the oath taken by a defendant together with compurgators in the procedure known as wager of law. A defendant who successfully "made his ley" — produced the required number of oath-helpers who would swear to his denial — was discharged of the claim. The phrase il tend sa ley au pleyntiffe (he tenders his law to the plaintiff) describes the moment at which a defendant formally offered to undergo this process.
Common Confusion
The two senses of ley — "law" in the general sense and "oath" in the wager-of-law sense — can mislead readers encountering the term in medieval and early modern texts. A phrase like il tend sa ley does not mean "he offers his legal argument" in any modern sense; it means he is formally offering to swear, with compurgators, to defeat the plaintiff's claim. Conflating these senses produces significant misreadings of early plea rolls and Year Book reports.
Why It Matters in Research
Researchers working in pre-modern English legal sources — Year Books, Britton, Bracton, early plea rolls, and similar materials — will encounter ley in both senses without any explicit signal as to which is meant. Context is essential: ley appearing in a title or descriptive phrase almost always means "law" generally; ley appearing in procedural context, especially in connection with a defendant's response to a claim, almost always refers to the oath-based procedure of wager of law.
The phrase Termes de la Ley is a bibliographic landmark researchers will encounter repeatedly. It is one of the earliest systematic legal glossaries in the English tradition, and citations to it in historical legal dictionaries — including Bouvier — carry weight because the text itself shaped the vocabulary of subsequent legal commentary.
The wager-of-law sense of ley is largely obsolete in substantive legal practice (the procedure was effectively abolished in England by the early nineteenth century), but it remains live for legal historians and anyone interpreting early common law records. Misunderstanding ley as merely "law" in a procedural context can cause a researcher to miss that the document describes a specific and highly technical pleading maneuver.
Corpus researchers should note that the Norman French spelling ley (rather than loi or law) is a reliable marker of age and register. Its presence in a text signals either medieval origin or a later author consciously drawing on archaic vocabulary.
Historical Dictionary Support
Bouvier's is economical on this term, offering both senses in a single brief entry. He gives the general meaning first — law, illustrated by Termes de la Ley — and then flags the "old technical sense" of oath or compurgatory swearing, citing Britton, chapter 27, for the phrase il tend sa ley au pleyntiffe. Bouvier's treatment is accurate as far as it goes, and the citation to Britton is useful because Britton (composed circa 1290s) is among the earliest systematic expositions of English common law and uses the Anglo-Norman legal register throughout.
What Bouvier does not do is explain the procedural mechanics behind the oath sense — the institution of wager of law, the role of compurgators, or the historical context in which a defendant's tender of ley was a meaningful litigation strategy rather than mere ceremony. Researchers needing that background should move from this entry directly to materials on wager of law. Bouvier's entry is a pointer, not a full account.
No other source dictionaries in the current corpus provide an entry for ley, which is consistent with its status as a term belonging primarily to the historical and Anglo-Norman legal register rather than to modern legal practice.
Jurisdictional Note
Ley in its wager-of-law sense is specific to the English common law tradition. Scots law, civil law jurisdictions, and canon law used related but distinct procedures; the term itself in this technical sense does not travel cleanly across those systems.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia — Wager of Law for the procedural institution underlying the oath sense of ley. See also Compurgation and Termes de la Ley (bibliographic entry) if available in the corpus.