Definition
Not guilty has two distinct legal meanings depending on context: it is both a plea entered by or on behalf of a criminal defendant, and a verdict returned by a jury (or judge) following trial.
1. As a plea: A defendant's formal response to a criminal charge denying the truth of the accusation and putting the prosecution to its proof. Entering a not guilty plea does not require the defendant to assert factual innocence — it is a procedural mechanism that joins the issue and requires the government to present evidence. A defendant may enter a not guilty plea even while privately acknowledging guilt. In practice, not guilty is the default plea in most jurisdictions; courts will enter it automatically when a defendant refuses to plead or stands mute.
2. As a verdict: The formal finding by a jury (or, in a bench trial, by the judge) that the prosecution has failed to prove the defendant's guilt beyond a reasonable doubt. A not guilty verdict results in acquittal and, under double jeopardy protections, bars retrial for the same offense. Critically, a not guilty verdict is not a finding of innocence — it is a finding that the evidence was legally insufficient to convict.
Common Language
Modern common usage (Wiktionary): "Of a person, legally innocent of a crime which they have been accused of in a court of law. Innocent."
Historical common usage: The phrase carried essentially the same meaning in ordinary usage — a denial of wrongdoing or a declaration of innocence.
The gap between common and legal meaning here is consequential. In ordinary English, "not guilty" and "innocent" are treated as synonyms. In law, they are not. A not guilty verdict resolves a legal proceeding; it does not establish innocence as a fact. Courts do not "find" innocence. Defendants are acquitted, not exonerated, by a not guilty verdict. This distinction matters intensely in post-acquittal civil proceedings, professional licensing actions, and immigration consequences, where an acquittal offers less protection than the common understanding of the phrase would suggest.
Common Confusion
NOT GUILTY vs. NOT GUILTY BY REASON OF INSANITY (NGRI): These are structurally different pleas with dramatically different outcomes. A standard not guilty plea contests whether the prosecution can prove the elements of the offense. NGRI concedes the act but asserts a defense that negates criminal responsibility. NGRI verdicts typically result in commitment proceedings, not release. Researchers encountering either plea in historical records should confirm which form was entered — older sources sometimes collapse the two.
NOT GUILTY vs. INNOCENT: Modern American criminal procedure does not recognize a formal verdict of "innocent." Some jurisdictions have introduced certificates of innocence or factual innocence findings through post-conviction statutes, but these are distinct from the trial verdict. The confusion persists in popular usage and occasionally in older legal commentary.
Recognized Forms
/SUBTYPES
Not Guilty by Reason of Insanity (NGRI): A specialized plea and potential verdict acknowledging the act while asserting that mental disease or defect negated criminal responsibility. Distinct procedural track; see encyclopedia entry on the Insanity Defense.
Not Guilty — General Issue: The historical common law form, entered in trespass and related actions, by which the defendant denied all material allegations and forced the plaintiff to prove the whole case. This is the form described in the historical dictionaries.
Not Guilty by Entrapment / Other Affirmative Defense: In some jurisdictions, a defendant may plead not guilty while relying on an affirmative defense such as entrapment, self-defense, or duress. The plea remains "not guilty" at the procedural level; the defense theory is developed at trial or through separate notice requirements.
Why It Matters in Research
Researchers working in historical common law sources will encounter "not guilty" almost exclusively as a plea to the general issue in trespass and trespass on the case — the civil action precursors to modern tort law. The historical dictionaries treat the plea in its civil context first. Modern researchers accustomed to thinking of "not guilty" as exclusively criminal must recognize this dual civil/criminal function in pre-19th century sources.
The shift matters for corpus navigation: cases indexed under "not guilty" in older reporters may be civil actions, not criminal prosecutions. Burrill's entry, for example, moves between the civil plea in trespass and the criminal plea without clear demarcation, reflecting an era when the procedural forms overlapped substantially.
In criminal procedure research, the not guilty plea's relationship to double jeopardy is a critical connection. Once jeopardy attaches and a not guilty verdict is returned, the constitutional bar is absolute under federal law. Historical sources predate the incorporation of double jeopardy protections against the states (not complete until Benton v. Maryland, 1969), so older treatises may describe state practices inconsistent with modern doctrine.
For immigration and collateral consequences research: the gap between acquittal and innocence has grown more significant as Congress and state legislatures have expanded civil consequences triggered by criminal involvement short of conviction. A not guilty verdict forecloses conviction-based consequences but does not necessarily foreclose consequences tied to arrest records, underlying conduct, or deferred adjudications.
Researchers using the Law Mind corpus should also note that guilty plea materials (see encyclopedia cross-reference) often discuss the not guilty plea as the baseline from which defendants depart — making that entry a necessary companion when researching plea bargaining, plea withdrawal, or collateral consequences.
Historical Dictionary Support
The historical dictionaries are in strong agreement on the core definition: not guilty is the general issue plea in trespass and criminal prosecutions, and the form of verdict by which a jury acquits. Black's (both editions) and Burrill track nearly identically, both citing Blackstone's Commentaries (4 Bl. Comm. 361) for the verdict form in criminal cases. Bouvier provides the most complete reproduction of the plea's formal language in trespass, grounding the entry in actual pleading practice.
Rapalje & Lawrence adds the useful clarification that in criminal law, not guilty is the appropriate plea where the prisoner wishes to "raise the general issue" — emphasizing that the plea's function is issue-joining, not factual declaration. This framing is more analytically precise than the other entries and usefully distinguishes the plea from special pleas or pleas in bar.
What the historical sources uniformly omit: any treatment of not guilty as a verdict's relationship to double jeopardy, any discussion of not guilty by reason of insanity as a separate plea form, and any analysis of the innocence/acquittal distinction. These are modern doctrinal developments that postdate the primary compilation periods of all four dictionaries. Researchers relying solely on these sources for modern criminal procedure questions will find them structurally incomplete.
Burrill's Latin and Law French references (non culpabilis; nient culpable) are useful for researchers tracing the plea's formal language through medieval and early modern English legal records.
Jurisdictional Note
The not guilty plea is universal across American state and federal criminal procedure, though the mechanics of entry vary. Some jurisdictions permit entry by counsel without the defendant's physical presence; others require the defendant to personally enter the plea. In bench trials, the not guilty verdict is styled as a finding rather than a jury verdict but carries identical legal effect. England and Wales retain the not guilty verdict form but have modified the procedural context considerably since the common law period reflected in the historical dictionaries.
Encyclopedia Cross-Reference
Guilty Pleas — Voluntariness, Collateral Consequences, and Withdrawal (The Law Mind Criminal Law Encyclopedia)
Insanity Defense — Guilty But Mentally Ill (GBMI) (The Law Mind Criminal Law Encyclopedia)