Definition
The petty jury (also spelled petit jury) is the trial jury — the body of ordinary citizens empaneled to hear evidence and return a verdict in a civil or criminal case. It is distinguished from the grand jury, which serves an investigative and accusatory function rather than a fact-finding one. In criminal cases, the petty jury determines guilt or innocence. In civil cases, it resolves disputed facts and, where applicable, awards damages.
The name derives from the French "petit" (small), referring to its size relative to the grand jury, not to any diminished importance. Standard composition is twelve jurors in serious criminal matters, though federal civil cases and many state courts permit fewer, and the precise number varies by jurisdiction and case type.
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Common Language
Modern common usage (Wiktionary): Listed as a synonym of "petit jury," with no independent definition offered.
Historical common usage (Webster's 1913): Not separately defined; subsumed under general jury entries.
The term "petty" in ordinary modern English carries a connotation of triviality or insignificance — the opposite of what this institution represents. A researcher encountering "petty jury" in older legal texts should understand the word carries no such dismissiveness. It is a transliteration of the French "petit," meaning simply "small" or "lesser in number," referring to size relative to the grand jury. The confusion is compounded by the existence of "petty larceny," where "petty" does signal minor severity — a completely different use of the same word appearing in the same legal sources.
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Common Confusion
PETTY JURY vs. GRAND JURY: These are the two distinct jury types in the Anglo-American system, and historical sources sometimes treat them under a single "jury" entry in ways that blur their separate functions. The grand jury indicts; the petty jury tries. The grand jury operates secretly and ex parte; the petty jury operates in open court with adversarial presentation. The constitutional protections attaching to each differ substantially. Researchers should not assume that doctrine governing one applies to the other.
PETTY JURY vs. PETTY LARCENY: Rapalje & Lawrence cross-references both "petty jury" and "petty larceny" in close proximity, directing readers to separate parent entries. The shared word "petty" is coincidental in effect — one signals size, the other signals severity. Do not conflate the doctrinal lineages.
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Why It Matters in Research
The petty jury sits at the center of the Sixth Amendment right to jury trial in criminal prosecutions and the Seventh Amendment right in federal civil cases, making it a constitutional term of art with a substantial body of doctrine attached to what seems like simple terminology.
Researchers working in historical sources will encounter both spellings — "petty jury" and "petit jury" — used interchangeably. Neither is more authoritative. Index searches in digitized primary sources should run both spellings, as editors were inconsistent across centuries of publication.
The question of jury size is a live research trap. The common law tradition of twelve jurors is not constitutionally mandated in all contexts. Federal and state rules diverge, and the line between cases requiring twelve jurors and those permitting fewer has shifted through case law. Researchers analyzing trial records from different periods or jurisdictions should not assume uniform composition.
In criminal matters, the unanimity requirement is another area where historical sources may mislead. The assumption of unanimous verdicts embedded in older treatises and dictionary definitions does not uniformly reflect modern doctrine across all jurisdictions.
The petty jury also connects directly to voir dire, challenge for cause, peremptory challenge, and jury nullification — all of which have independent doctrinal histories that researchers may need to trace alongside the petty jury itself.
Rapalje & Lawrence's sparse treatment — a single cross-reference to the general JURY entry — is typical of how historical dictionaries handled the term. The substantive doctrine was deposited in the parent "jury" entry, meaning researchers using period dictionaries must follow those cross-references to find usable content.
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Historical Dictionary Support
Rapalje & Lawrence (1883) offers only a redirect: "See JURY, 7." This tells a researcher two things. First, the editors treated petty jury as a subtype of the general jury concept, not as a freestanding institution requiring its own entry. Second, the cross-reference to a numbered subsection suggests the JURY entry was organized to address petty jury as one of several recognized jury forms. Researchers using Rapalje & Lawrence should go directly to JURY, 7 for the substantive treatment.
The absence of a standalone definition in this source is not unusual for the period. Nineteenth-century legal dictionaries frequently concentrated doctrinal content at the parent term and used cross-references economically. The limitation for modern researchers is that these parent entries can be long and undifferentiated, requiring careful reading to isolate petty jury doctrine from grand jury and special jury material that may appear in the same section.
No historical dictionary in the present source set offers a full definition. Researchers needing period-specific doctrinal content should consult the primary treatise literature — Blackstone's Commentaries, and later Greenleaf on Evidence — where the petty jury's function, composition, and procedural requirements are treated at length.
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Jurisdictional Note
Jury trial rights, jury size, and unanimity requirements vary between federal and state courts and among states. The constitutional floor established by the Sixth and Seventh Amendments does not resolve all questions of composition or procedure, and state constitutional provisions frequently impose independent requirements. Research into petty jury doctrine must identify the governing jurisdiction before relying on any general statement of the law.
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Encyclopedia Cross-Reference
See The Law Mind Criminal Law Encyclopedia: Mistrial and Hung Jury (criminal_212); Grand Jury — Function, Procedure, and Powers (criminal_168); Grand Jury — Fifth Amendment in Grand Jury Proceedings (criminal_169).
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