Definition
A Latin particle meaning "that." In legal usage, *illud* appears almost exclusively as the opening word of Latin maxims rather than as a standalone legal term. It functions grammatically as a demonstrative pronoun, equivalent to "that which" when followed by a relative clause. The word itself carries no independent legal doctrine; its significance lies entirely in the maxims it introduces.
Two maxims built on *illud* appear with regularity in the classical legal literature:
1. *Illud quod alias licitum non est, necessitas facit licitum; et necessitas inducit privilegium quoad jura privata.* — "That which is otherwise not permitted, necessity permits; and necessity creates a privilege as to private rights." This maxim articulates the doctrine of necessity as a source of legal privilege, suspending ordinary legal prohibitions when compelled by circumstances beyond a party's control.
2. *Illud quod alteri unitur, extinguitur, neque amplius per se vacare licet.* — "That which is united to another is extinguished, and can no longer exist independently." This maxim appears in ecclesiastical property law to describe the merger or annexation of a benefice or estate into a larger whole, after which the absorbed interest ceases to have a separate legal existence.
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Common Confusion
*Illud* is occasionally run together with neighboring headwords in poorly formatted editions of the historical dictionaries, most commonly with *illusory* or entries under *imam/imaum*. This is a typographical artifact of nineteenth-century printing and digitization, not a substantive connection. The proximity to *illusory appointment* material in Burrill's text has no legal relationship to *illud* as a Latin particle.
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Why It Matters in Research
Researchers will rarely encounter *illud* as a headword they need to look up directly. Its practical importance is navigational: recognizing it as a maxim-opener rather than a substantive term prevents misreading historical sources. When a case, treatise, or pleading quotes a Latin maxim beginning with *illud*, the researcher should locate the maxim as a whole, not treat *illud* as the operative concept.
The necessity maxim (*illud quod alias licitum non est*) connects directly to a live area of substantive law. The doctrine of necessity — that compulsion by circumstances creates privilege — recurs in criminal defense, property encroachment cases, admiralty, and emergency government action. Tracing this maxim into English common law sources leads through Bracton and Bacon's *Maxims* and then forward into modern necessity doctrine. Researchers working on those substantive questions should follow the necessity thread, not linger on *illud* itself.
The merger maxim (*illud quod alteri unitur*) is primarily relevant to ecclesiastical law and historical property research involving the annexation or consolidation of church benefices and livings. Godolphin's *Abridgment of the Ecclesiastical Laws* is the cited source in the classical dictionaries, making it the natural starting point for that line of inquiry.
A practical trap: the source dictionaries print these maxims with visible OCR errors and broken formatting. Black's (1st ed.) and Black's (2nd ed.) both show corrupted text around the *illud* entries — garbled characters, run-on headwords, and text from adjacent entries bleeding in. Researchers relying on digitized versions should verify maxim text against clean manuscript or print editions of Bracton and Bacon's *Maxims* before quoting.
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Historical Dictionary Support
All three source dictionaries treat *illud* identically: a brief Latin gloss ("That") followed by one or two maxims with citations. None develops *illud* as an independent legal concept, which correctly reflects its grammatical rather than substantive role.
Burrill's entry is the cleanest, rendering the necessity maxim accurately and citing Bracton, fol. 247, alongside a reference to Kent's *Commentaries* on illusory appointments — though the Kent material appears to have bled in from a neighboring entry (*illusory*) in Burrill's original text, and does not belong to *illud* as a term.
Black's (2nd ed.) supplies the merger maxim with a citation to Godolphin's *Ecclesiastical Law*, which the 1st edition omits, making the 2nd edition slightly more complete for ecclesiastical property research.
No historical dictionary entry provides meaningful analysis of the maxims themselves. For the substance of the necessity doctrine embedded in the first maxim, researchers must go to the primary sources: Bacon, *Maxims of the Law* (Rule 5 addresses necessity and private right); and for the ecclesiastical merger doctrine, Godolphin, *Repertorium Canonicum* or the *Abridgment of the Ecclesiastical Laws*.
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