Definition
A hung jury is a jury that, after good-faith deliberation, cannot reach the verdict required to resolve a case. The result is neither an acquittal nor a conviction — the jury simply fails to agree, and the court declares a mistrial. The case does not end; the prosecution may retry the defendant before a new jury.
The term applies in both criminal and civil proceedings, though it arises most consequentially in criminal cases where the stakes of unanimity are highest.
Common Language
Modern common usage (Wiktionary): A jury in a legal trial that is unable to reach a unanimous or required supermajority verdict after extended deliberation.
Historical common usage (Webster's 1913): No entry. The phrase was not recorded as a general vocabulary term in Webster's 1913, reflecting its status as legal-professional shorthand rather than common speech.
The common and legal meanings are closely aligned today, but the phrase carries a precision in legal usage that casual reference can obscure. "Hung" describes the state of the jury, not any outcome of the case itself — a point that matters when researchers encounter the term in historical records where a hung jury might be recorded simply as a mistrial or a discharge without verdict, with no indication of what happened next.
Common Confusion
HUNG JURY vs. MISTRIAL: A hung jury causes a mistrial, but not all mistrials result from a hung jury. A mistrial may be declared for juror misconduct, prejudicial error, death or incapacity of a juror, or procedural breakdown. When researching historical records, a mistrial entry does not necessarily mean the jury deadlocked — check surrounding documentation for the actual basis of discharge.
HUNG JURY vs. ACQUITTAL: A hung jury is not an acquittal and does not trigger double jeopardy protections barring retrial. This is a frequent point of confusion in popular accounts of criminal cases. An acquittal requires the jury to return a formal not-guilty verdict. A deadlock produces no verdict at all.
Why It Matters in Research
The hung jury sits at a procedural crossroads that generates significant research complexity.
First, the vocabulary shifts across time and jurisdiction. Older American court records — particularly 19th-century state court minutes — may record the outcome as "jury discharged without agreement," "jury unable to agree," or simply "mistrial" without specifying deadlock as the cause. Researchers working in historical court records should not assume that "mistrial" equals hung jury or that silence on the point means acquittal.
Second, the unanimity requirement — which underlies most hung jury outcomes — has its own complicated history. Federal criminal trials have long required unanimous jury verdicts. State criminal practice varied historically, and the constitutional requirement of unanimity in state felony trials was not firmly established by the Supreme Court until Ramos v. Louisiana (2020). Before that ruling, Louisiana and Oregon allowed non-unanimous verdicts in serious criminal cases, meaning that what would produce a hung jury in a federal court or most state courts might have produced a valid conviction in those jurisdictions. Corpus materials from Louisiana and Oregon pre-2020 must be read with this in mind.
Third, the hung jury is an important variable in empirical and historical studies of jury behavior, prosecutorial discretion, and case outcome patterns. When a hung jury appears in research materials, the immediate next question is whether the case was retried — and if so, what the outcome was. Court records frequently do not link these proceedings automatically, and a researcher may encounter the original deadlock without any indication that a retrial followed.
Fourth, hung jury outcomes interact with double jeopardy doctrine in nuanced ways. Because a hung jury produces no verdict, retrial is constitutionally permissible under the Double Jeopardy Clause. But the boundaries of that rule — particularly when a jury hangs on some counts but not others — can affect what charges may be brought in a subsequent proceeding. Researchers working on double jeopardy questions should treat a hung jury record as the beginning of the inquiry, not the end.
Historical Dictionary Support
Black's Law Dictionary (2nd Ed.) offers a compact and accurate baseline: "A jury so irreconcilably divided in opinion that they cannot agree upon any verdict." This definition correctly captures the essential feature — the division is irreconcilable within the deliberation — without addressing the procedural consequences.
What the historical dictionary entry does not address: the distinction between a hung jury and other grounds for mistrial; the relationship to double jeopardy and retrial; the unanimity requirement and its evolution; or the variation between civil and criminal contexts. Researchers relying solely on this definition for historical source interpretation will have an accurate but incomplete picture. The entry is sufficient for identifying what the term meant, but not for understanding its procedural significance in a specific case record.
No substantial divergence exists between historical dictionary treatment and modern usage on the core meaning. The term has been stable. What has changed is the constitutional and procedural scaffolding around it, particularly regarding unanimity requirements in state courts.
Jurisdictional Note
The unanimity requirement that typically produces a hung jury is now constitutionally mandated in federal and state criminal trials following Ramos v. Louisiana (2020). Pre-2020 materials from Louisiana and Oregon may reflect non-unanimous verdict rules, which affect how "hung jury" situations were defined and recorded in those jurisdictions. Civil cases operate under different standards — federal civil juries may render verdicts by five-sixths majority under certain conditions — so the threshold for a hung jury in civil proceedings varies.
Encyclopedia Cross-Reference
Mistrial and Hung Jury — The Law Mind Criminal Law Encyclopedia (criminal_212)
Grand Jury: Function, Procedure, and Powers — The Law Mind Criminal Law Encyclopedia (criminal_168) [for contrast with grand jury deadlock, which operates under different rules]