Definition
Ex intervallo is a Latin phrase meaning "after an interval" or "after a lapse of time." In legal usage, it describes an act, declaration, or legal consequence that occurs following a gap or intervening period — as distinguished from something done immediately, simultaneously, or in the heat of the moment.
The phrase appears most frequently in older common law contexts relating to lucid intervals in mental incapacity cases. A person otherwise regarded as mentally incompetent might be capable of forming valid legal intent — to execute a will, enter a contract, or commit a crime with requisite mens rea — if the act was performed ex intervallo, during a period of restored mental clarity. The interval in question is the gap between episodes of incapacity.
Why It Matters in Research
This term is almost exclusively a term of historical legal Latin and will appear primarily in pre-20th century common law sources — treatises, reports, and pleading books — rather than in modern statutes or judicial opinions. Researchers encountering it in historical texts should resist reading it as a procedural or temporal term of art in the modern sense; its force is contextual and depends heavily on the surrounding doctrine.
The most important research context is the law of testamentary capacity and criminal responsibility. When a historical source describes a testator or defendant acting ex intervallo, the key question is whether the interval was sufficiently lucid — a factual and medical determination that courts treated as a jury question. The phrase therefore often signals a contested evidentiary issue in the underlying record, not a settled legal conclusion.
Researchers working in probate, wills, or insanity defense history should treat ex intervallo as a flag pointing to surrounding doctrine about lucid intervals (lucida intervalla). The two concepts are closely linked: ex intervallo describes the timing of the act; lucida intervalla describes the legal status of the mental state during that time. Do not conflate them.
The Fleta citation in Burrill — lib. 2, c. 60, § 2 — places this term firmly in the medieval English legal tradition. Fleta is a late 13th-century Latin treatise on English law, and its usage here reflects the early common law treatment of mental incapacity as episodic rather than continuous. Researchers using Fleta should note that the text survives in manuscript and early printed editions and that modern scholarship has identified authorship and dating uncertainties; the passage should be treated as evidence of medieval doctrine, not authoritative precedent.
Historical Dictionary Support
Burrill's Law Dictionary provides the core entry: "After an interval," with a single citation to Fleta. This is a characteristically spare Burrill entry — accurate as far as it goes, but offering no doctrinal elaboration. Burrill does not explain the legal context in which the phrase operates, leaving the researcher to supply that from surrounding common law doctrine.
No other Law Mind shelf sources include this term, which reflects its status as a minor Latin phrase of art rather than a major doctrinal term. Its absence from later American dictionaries (such as Black's) suggests it was already receding from active legal usage by the mid-19th century, absorbed into the more developed doctrine of lucid intervals without needing its own term.
Jurisdictional Note
This is a historical common law term with no distinct American jurisdictional variation. Its practical relevance is confined to historical English and early American legal sources. Modern courts do not use the phrase.