Definition
A Latin phrase meaning "other things being equal" or "all else being equal." Used in legal and analytical contexts to isolate a single variable for comparison or argument while holding all other relevant conditions constant. In legal writing, caeteris paribus typically appears when a writer wishes to draw a comparison between two situations, cases, or outcomes that are treated as otherwise identical — so that any difference in result can be attributed solely to the factor under examination.
The phrase is borrowed from classical logic and economics and functions in legal discourse primarily as a rhetorical or analytical tool rather than as a term of art with formal doctrinal content. It appears most frequently in treatises, academic commentary, judicial dicta, and arguments comparing precedents.
Why It Matters in Research
Researchers are unlikely to encounter caeteris paribus as an operative legal term in statutes, jury instructions, or pleadings. Its appearances in the corpus cluster in two places: (1) older treatise writing and common law commentary, where Latin scholarly vocabulary was standard; and (2) judicial opinions engaging in comparative analysis, often when distinguishing cases on narrow grounds.
When you find this phrase in a historical source, treat it as a signal that the author is about to draw a narrow comparison — the surrounding argument is likely identifying a single distinguishing fact or legal element. This makes it a useful phrase to scan for when tracing how courts or commentators justified treating two superficially similar cases differently.
Modern legal writing has largely replaced the phrase with plain-English equivalents: "all else being equal," "holding all other factors constant," or "on otherwise identical facts." If you are searching for analogous reasoning in modern sources, the Latin phrase alone will not surface all relevant passages.
Because this is an analytical phrase and not a doctrine, there is no meaningful jurisdictional variation and no formal test or elements structure attached to it.
Historical Dictionary Support
Bouvier's entry is characteristically sparse: "Other things being equal. Black." — a bare translation followed only by a citation to Black's Law Dictionary, with no elaboration. This suggests that by the mid-nineteenth century the phrase was considered well-understood among legally trained readers and required no further gloss.
Bouvier's brevity is itself instructive. The phrase carried no distinct legal meaning beyond its classical sense; it was included in legal dictionaries as a courtesy to practitioners encountering Latin in learned sources, not because it had developed independent doctrinal weight. Historical legal dictionaries agree on the translation and share the same minimal treatment — none develop a specifically legal application separate from the phrase's general logical meaning.
What the historical dictionaries do not address is how the phrase functions rhetorically in legal argument — its role in structuring comparative reasoning. That analytical dimension is entirely omitted from nineteenth-century legal dictionary entries, which treated it as a vocabulary item rather than an argumentative move.