Definition
Applicable and relevant to the matter at hand. In legal usage, evidence or an argument is pertinent when it is directed to the issues or facts in dispute and legitimately tends to prove or disprove the allegations of the party offering it. A pertinent hypothesis is one that, if sustained, would logically influence the outcome of the issue being decided. The term functions as a threshold descriptor in evidentiary and procedural contexts, distinguishing material that properly bears on a dispute from material that does not.
Common Language
Modern common usage (Wiktionary): Relevant or applicable to a particular matter; to the point.
Historical common usage (Webster's 1913): Belonging or related to the subject or matter in hand; fit or appropriate in any way; adapted to the end proposed; apposite; material; relevant.
The common and legal meanings are closely aligned in their core sense, but the legal meaning carries a functional edge: pertinence in law is not merely topical relevance but a capacity to legitimately tend to prove or disprove a specific allegation. Something can be broadly related to a subject and still be legally impertinent if it does not bear on the actual issue in dispute.
Common Confusion
Pertinent and relevant are used interchangeably in many historical legal sources, and in modern practice the two have largely merged. However, historical dictionaries treated them as subtly distinct: relevant referred to logical connection to the issue, while pertinent carried an additional implication of fitness or appropriateness—the idea that the evidence not only connects to the issue but legitimately tends to prove what it is offered to prove. Researchers should not assume the two terms were always synonymous in older sources.
The natural antonym in legal writing is impertinent, not irrelevant. Historical pleading practice used impertinence as a formal term of art for matter included in a pleading that had no bearing on the issue—a distinct procedural concept with its own remedies. Modern researchers encountering impertinent in older equity pleadings should not read it simply as the opposite of relevant; it carried procedural weight.
Why It Matters in Research
Pertinent appears most frequently in two distinct historical contexts that researchers should distinguish: evidentiary questions (whether a piece of evidence tends to prove an allegation) and pleading questions (whether matter included in a bill or pleading legitimately belongs there). Conflating these contexts can produce misreadings of older cases and treatises.
In evidentiary sources, pertinent functions as a near-synonym for relevant but with slightly different connotations depending on era and jurisdiction. In sources predating the Federal Rules of Evidence and equivalent state codifications, pertinent and relevant both appear, sometimes in the same sentence, sometimes with shading between them. After mid-twentieth century codification, relevant largely displaced pertinent as the operative term in evidence law, though pertinent survives in some statutory and regulatory contexts (notably in contempt of Congress proceedings and legislative investigations, where "pertinent question" carries specific legal meaning).
In equity pleading and chancery practice, impertinence was a formal objection and pertinent its implied opposite. Researchers working in pre-twentieth-century equity materials need to understand this procedural dimension, which is not captured by modern evidence doctrine.
Corpus researchers should also note that pertinent appears in constitutional and legislative contexts—particularly in the law of legislative investigations—where "pertinency" is a due process requirement: a witness cannot be held in contempt for refusing to answer a question unless the pertinency of the question to the subject under inquiry was made clear at the time. This is a distinct and developed body of doctrine, not merely an evidentiary use of the word.
Historical Dictionary Support
The four source dictionaries present a consistent but thin account. All four agree that pertinent means applicable or relevant, and all four define it functionally by reference to what it does: evidence is pertinent when it tends to prove or disprove the allegations of the parties. Bouvier traces the word to the Latin pertineo (to belong to) and cites Willes 319 as authority, grounding the definition in its logical relationship to party allegations rather than to abstract truth. Anderson adds useful cross-references to impertinence and relevant, signaling that the term should be read within a network of related concepts rather than in isolation.
Black's second edition adds the pertinent hypothesis formulation from Whitaker v. State, which is the most analytically useful framing in the historical sources: a hypothesis is pertinent if, when sustained, it would logically influence the issue. This moves the definition from descriptive to functional and reflects how courts actually deployed the concept.
What the historical dictionaries largely miss is the legislative investigation context, in which pertinency became a constitutional requirement with its own doctrine. They also do not address the trajectory by which relevant largely absorbed pertinent in modern codified evidence law, leaving pertinent to survive in specialized pockets.
Jurisdictional Note
In federal law, pertinency doctrine in the legislative investigation context has constitutional dimensions developed through Supreme Court decisions. In evidence law generally, modern codified systems use relevant and relevance as the operative terms, and pertinent functions mainly as a descriptive synonym. Researchers in jurisdictions with older, uncodified evidence traditions may find pertinent used more precisely and distinctly from relevant in the case law.