Definition
Intelligibility in law carries two distinct and largely independent meanings, one rooted in pleading doctrine and the other in constitutional administrative law.
1. Pleading (historical). In common law pleading, intelligibility was a formal requirement that allegations be stated so plainly and directly that a person of ordinary understanding could grasp their meaning without inference, argument, or construction. The test was not whether a trained lawyer could decode the pleading, but whether an ordinary reader could. Statements that required reasoning to reach their meaning failed the standard.
2. Constitutional administrative law (intelligible principle). In the nondelegation doctrine, intelligibility refers to the constitutional requirement that when Congress delegates legislative power to an executive agency, it must supply an intelligible principle — a discernible standard — by which the agency is to exercise that delegated authority. A statute that grants regulatory power without any such guiding principle is, in theory, an unconstitutional delegation of legislative power to a non-legislative body.
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Common Language
Modern common usage (Wiktionary): The degree to which something is intelligible; in reference to recorded speech, the quality of every word being understandable.
Historical common usage (Webster's 1913): The quality or state of being intelligible; clearness; perspicuity; definiteness.
Editorial note: Common usage treats intelligibility as a property of communication — how clearly a message comes through. The legal meanings retain this core sense but redirect it: in pleading, intelligibility is a formal drafting requirement measured against the comprehension of an ordinary person; in constitutional law, it is a structural standard governing how much guidance Congress must give before handing power to an agency. Neither legal use is about audibility or mere clarity of expression in the everyday sense.
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Recognized Forms
/SUBTYPES
Intelligibility in pleading. The traditional pleading requirement that facts be stated directly, without requiring inference or legal argument to arrive at their meaning. Distinct from the requirements of certainty and precision, though all three often appeared together as interlocking pleading standards.
Intelligible principle (nondelegation). The constitutional test articulated in J.W. Hampton, Jr. & Co. v. United States (1928), requiring that legislation delegating authority to an executive body lay down an intelligible principle to which the person or body authorized to act is directed to conform. This is the live constitutional doctrine; the pleading sense has largely receded with the displacement of common law pleading by modern procedural codes.
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Why It Matters in Research
Researchers face a significant disambiguation problem. Searching "intelligibility" in the Law Mind corpus will surface sources across at least two unrelated legal contexts — pleading doctrine and constitutional delegation — and the term's weight and usage shifted dramatically across time. In nineteenth-century treatises and case law, intelligibility is almost always a pleading concept. In twentieth- and twenty-first-century sources, it is far more likely to mean the intelligible principle test in administrative and constitutional law. Conflating these two contexts will produce noise in research.
For pleading research: Black's (2nd Ed.) connects intelligibility to the formal common law pleading system. Researchers using older case reporters should expect the term to appear in connection with demurrers, motions in arrest of judgment, and challenges to declarations or indictments. The standard was frequently paired with certainty and definiteness. Modern civil procedure has largely replaced this vocabulary — Federal Rule of Civil Procedure 8's notice pleading standard renders the formal intelligibility requirement obsolete in federal practice, though it may persist in states with code pleading traditions.
For nondelegation research: The intelligible principle doctrine is one of the most contested and evolving areas of administrative and constitutional law. Corpus sources on this doctrine span from the New Deal era through contemporary Supreme Court debates about whether the intelligible principle standard should be tightened or abandoned. Researchers should connect this entry to the administrative law encyclopedia entry for the fullest treatment of how this doctrine has shifted.
A third, narrower research context may also appear: Miranda and waiver doctrine uses "intelligent" and related language to describe the knowing-and-intelligent standard for waiver of constitutional rights. This is conceptually adjacent but doctrinally separate — do not conflate intelligibility-as-pleading-standard or intelligibility-as-nondelegation with the intelligent-waiver requirement.
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Historical Dictionary Support
Black's Law Dictionary (2nd Ed.) defines intelligibility exclusively in the pleading context, reflecting the period in which that edition was compiled. The definition is precise and technically accurate for its era: statements of fact must be direct, must exclude the necessity of inference or argument, and must be arranged so as to be comprehensible to a person of ordinary understanding. The three cases Black's cites — Merrill v. Everett, Davis v. Trump, and Jennings v. State — situate the term in the context of civil declarations and criminal pleading challenges.
What the historical dictionary entry does not capture is the constitutional administrative law meaning, which postdates the 2nd Edition. The intelligible principle formulation emerged in the early twentieth century and became a central feature of administrative law doctrine through the New Deal period and beyond. Any researcher relying solely on historical dictionary sources will miss this — the dominant modern legal use of the word is entirely absent from Black's (2nd Ed.).
Webster's 1913 and Wiktionary both preserve the ordinary-language sense (clearness, comprehensibility), which aligns well with the pleading definition but offers no purchase on the constitutional doctrine. The gap between dictionary generations here is substantive, not cosmetic.
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Jurisdictional Note
The intelligible principle test in its constitutional form is a federal doctrine, rooted in the Vesting and Nondelegation principles of the U.S. Constitution. State constitutions impose analogous — but often independently developed — nondelegation requirements, and the stringency of those standards varies considerably. The pleading-era intelligibility requirement survives more robustly in states that retained code pleading rather than adopting notice pleading rules modeled on the Federal Rules of Civil Procedure.
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Encyclopedia Cross-Reference
Delegation of Legislative Power — Nondelegation Doctrine and Intelligible Principle (The Law Mind Administrative Law & Government Encyclopedia)
Miranda — Waiver (Knowing, Voluntary, and Intelligent) (The Law Mind Criminal Law Encyclopedia)
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