Definition
Latin maxim meaning "it runs on four feet" — used in legal argument and judicial writing to assert that a precedent, analogy, or comparison corresponds exactly to the case at hand in all material respects. When a case or rule is said to run quatuor pedibus, it is a complete match: the facts align, the legal principle applies, and no meaningful distinction can be drawn. The phrase is the affirmative counterpart to the cautionary maxim nullum simile quatuor pedibus currit — "no analogy runs on all fours" — which warns against over-extending a comparison or treating any parallel as perfect.
In practice, the term functions as rhetorical shorthand for "on all fours," signaling either (a) that a cited authority controls the present case without qualification, or (b) that the analogy being drawn holds across every relevant dimension.
Common Confusion
Quatuor pedibus currit and its negative form nullum simile quatuor pedibus currit are sometimes treated as contradictory principles rather than complementary tools. They are not in conflict. The affirmative form is a claim about a specific precedent or analogy — that it happens to match precisely. The negative form is a general caution about the limits of analogical reasoning. Both can be true simultaneously: a lawyer may assert that a particular case runs quatuor pedibus while acknowledging that, as a general matter, analogies rarely do. Researchers should read the surrounding argument carefully to determine which function the phrase is serving.
Why It Matters in Research
This term is almost exclusively a historical artifact of common law pleading and advocacy style. Researchers encountering it in primary sources — judicial opinions, treatises, counsel arguments — should understand it as a stylized marker of analogical confidence, not a term of art with defined legal elements or doctrinal consequences.
Several research traps deserve attention:
First, the phrase appears far more frequently in abbreviated or translated form. Sources that cite a case as being "on all fours" are invoking the same concept without the Latin. Corpus searches limited to the Latin phrase will substantially undercount the idea's presence in the literature. Cross-searching "on all fours," "runs upon all fours," and "quatuor pedibus" together is necessary for comprehensive retrieval.
Second, Burrill's entry preserves the most instructive use: the 1 W. Bl. 145 quotation, where the court explicitly denies that a trust and an equity of redemption run quatuor pedibus. This negative deployment — asserting that two things do not correspond exactly — is equally common in the sources and equally important. Researchers should not assume the phrase always appears as an affirmative claim.
Third, frequency of this Latin form declines sharply through the nineteenth century as courts shifted to English equivalents. Pre-1800 English reports and early American decisions are the richest hunting ground for the Latin phrase itself; later sources overwhelmingly prefer "on all fours."
Fourth, the Coke citation embedded in Burrill (Co. Litt. 3a) for the negative maxim is a genuine anchor point. Researchers tracing the intellectual lineage of analogical reasoning doctrine in the common law should treat that locus as a starting point, not an endpoint.
Historical Dictionary Support
All three source dictionaries agree completely on the core meaning: "runs upon four feet; runs upon all fours." Black's (both editions) treats the entry as a pure cross-reference to ALL-FOURS and adds no independent analysis. Burrill goes further and is the more useful source for researchers, offering the negative maxim, a Coke citation, and a live quotation from Blackstone's Reports (1 W. Bl. 145) demonstrating the phrase in context.
The historical dictionaries do not address the rhetorical mechanics of how the phrase functioned in argument — whether as a claim of factual identity, legal identity, or both. That ambiguity is left entirely to context. Burrill's inclusion of the negative maxim is the single most valuable contribution across the three sources, because it captures the tradition of epistemic humility that surrounds analogical reasoning in common law method: the very same legal culture that praised a good analogy also institutionalized the reminder that no analogy is perfect.
What the historical dictionaries collectively miss is any treatment of the phrase's decline and its displacement by the English vernacular equivalent. A researcher relying solely on these entries would not appreciate how rapidly the Latin form fell out of active use or how completely "on all fours" absorbed its function.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Analogical Reasoning in Common Law Argument; Maxims of Law.