Definition
A datu is a Law Latin phrase meaning "from the date." It appears in historical legal documents, particularly deeds and instruments, to mark the starting point from which a period of time is computed — that is, from the date of the instrument itself, as opposed to from delivery, from sealing, or from some other triggering event.
The phrase appears in several closely related forms across historical sources:
1. A datu — from the date (the base form; see Cro. Jac. 135).
2. A die datus — from the day of the date (a more explicit formulation specifying the calendar day rather than the date-event generally).
3. A dato — an alternate rendering, functionally equivalent.
In practice, the distinction between these forms is terminological rather than substantive. All three anchor the computation of a time period — such as a lease term, a bond's running time, or a condition's deadline — to the date written on the face of the instrument.
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Common Confusion
A datu is sometimes run together visually with a dato and a die datus in historical sources, as if they are meaningfully distinct doctrines. They are not — all three are variants expressing the same idea: the computation runs from the date on the instrument's face. The variation reflects scribal and editorial conventions across different reporters and centuries, not distinct legal rules.
Researchers should also be alert to the editorial collision in the historical dictionary entries: the maxim A digniori fieri debet denominatio is appended to the a datu entries in all three dictionaries. These are separate entries sharing alphabetical proximity, not parts of a single definition.
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Why It Matters in Research
The practical significance of a datu lies in time computation disputes. In historical property and contract law, how a period was measured — from the date, from delivery, from sealing, from acknowledgment — could determine whether an obligation had ripened or expired. A datu was one of several competing anchor points, and courts sometimes had to resolve which controlled when an instrument was silent or ambiguous.
Researchers working in early English real property records, conveyancing manuals, or reports from the late seventeenth and early eighteenth centuries will encounter this phrase in the context of lease terms and bond conditions. The citations in the historical dictionaries point to Salkeld's Reports (2 Salk. 413), Lord Raymond's Reports (1 Ld. Raym. 84, 480; 2 Ld. Raym. 1242), and Croke's Jacobean Reports (Cro. Jac. 135) — all English common law reporters of the early modern period. Crabb's Real Property (2 Crabb, Real Prop. p. 248, § 1301) remains a useful secondary source for understanding how dates functioned in conveyancing contexts.
The phrase has no meaningful modern American legal usage. Researchers encountering it should treat it as a signal that the surrounding text involves time-period computation under early English common law conventions, not a substantive legal doctrine in its own right.
Note also that the historical dictionary entries append a separate maxim — A digniori fieri debet denominatio ("Denomination ought to be from the more worthy") — as a distinct entry beginning with the same letter sequence. That maxim concerns the description of a place, instructing that a location should be identified by its more dignified or significant feature. It is unrelated to date computation and is included in the dictionary entries only by alphabetical proximity.
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Historical Dictionary Support
Black's (1st Ed.), Burrill's, and Black's (2nd Ed.) are in full agreement on the meaning of a datu. All three define it as "from the date" and cite overlapping authority — principally Salkeld, Lord Raymond, and Croke Jacobean. The entries are nearly identical in substance, with minor variation in citation form. Burrill's is slightly fuller in its cross-references, directing the reader to see also "Datus, Datum, Date," which reflects Burrill's general practice of building internal dictionary networks around Latin root forms.
None of the historical entries explain why the distinction between a datu, a die datus, and a dato mattered in practice — they report the phrase without contextual illustration of the legal disputes that generated the case authority. Researchers needing to understand the operative significance in a specific case or document will need to consult the underlying reporters directly rather than relying on dictionary treatment alone.
Black's 2nd Ed. identifies the case behind "2 Salk. 413" as Haths v. Ash (also rendered Hatter v. Ash at 1 Ld. Raym. 84), providing a case name that the 1st Ed. omits.
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