Definition
A Latin term used in old English law meaning to turn aside, divert, or alter the course of something — most commonly applied to watercourses or roads. Two principal uses appear in the historical sources:
1. Diversion of a watercourse: To turn a stream from its natural channel. The phrase aqua trestornata designated a stream that had been diverted from its course, and actions de aquis trestornatis addressed legal wrongs arising from such diversions.
2. Alteration of a road: To turn or change the established course of a road, disrupting the customary passage recognized by law.
The term does not appear in modern legal usage. It belongs exclusively to the vocabulary of medieval English law as recorded in Bracton and Fleta, and it surfaces in legal dictionaries as a term of art for historical reference rather than active practice.
Why It Matters in Research
Researchers encountering trestornare will find it almost exclusively in Latin legal texts of the thirteenth and fourteenth centuries — principally Bracton's De Legibus et Consuetudinibus Angliae and Fleta. These sources address the legal consequences of interfering with established watercourses and roads, topics that connect to early property and nuisance doctrine.
The relevance today is primarily historical. Disputes over water diversion and road alteration were serious matters in medieval common law, implicating riparian rights and rights of way that have evolved substantially in both English and American law. A researcher tracing the doctrinal roots of riparian water rights, easements, or public road law may encounter trestornare in primary Latin sources without finding it explained in modern commentaries. The historical dictionaries provide the entry point, but researchers will need to consult Bracton and Fleta directly for context.
Note that Burrill's entry contains an apparent printing or transcription corruption — a passage about "examination of the matter of fact in issue" and trial procedure appears interpolated mid-definition, unrelated to trestornare. This is almost certainly a typesetting error from the original edition, where text from an adjacent or nearby entry bled into this one. Researchers relying on Burrill's for this term should treat that passage as extraneous and not as part of the definition.
The folio references across all three dictionaries (Bract. fols. 115, 234b; Fleta lib. 2, c. 52, § 18) are consistent and point to verifiable primary sources, making them reliable starting points for deeper research.
Historical Dictionary Support
All three source dictionaries are in close agreement on substance. Black's (1st and 2nd editions) and Burrill's each identify both meanings — diversion of a watercourse and alteration of a road — and all cite Bracton and Cowell as authority. Burrill adds the Fleta citation and provides the phrase de aquis trestornatis, which is useful for locating related passages in the primary sources.
Cowell's Interpreter, cited by both Black's editions for the road-alteration meaning, was a standard reference for archaic legal Latin through the early modern period and lends support to that secondary application of the term.
None of the historical dictionaries discuss the legal consequences that attached to trestornare — what remedies or actions were available, who could bring them, or what defenses existed. For that doctrinal content, Bracton and Fleta remain the only practical sources. The dictionaries function here as finding aids rather than comprehensive treatments.