Definition
A spring gun is a firearm or other lethal device rigged to discharge automatically when a person disturbs a tripwire, cord, pressure plate, or similar triggering mechanism. The weapon fires without a human operator present at the moment of discharge. Spring guns have historically been deployed by property owners to deter or injure trespassers and burglars, typically positioned at points of entry such as windows or doors.
In legal usage, the term encompasses the device itself and the act of setting such a device. The law addresses spring guns primarily in two contexts: (1) criminal liability for the person who sets the device, and (2) civil tort liability to anyone injured by it.
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Common Language
Modern common usage (Wiktionary): A gun rigged to fire when a tripwire is crossed.
Historical common usage (Webster's 1913): A gun or firearm so arranged as to be discharged by the action of an animal or person coming in contact with a wire or thread connecting with the trigger.
The common meaning captures the mechanical description accurately. The legal gap is in consequence: ordinary usage treats the spring gun as a curiosity or historical artifact, while legal usage centers on the serious criminal and civil liability that flows from setting one. A researcher encountering "spring gun" in a legal source should read it as a term of liability, not merely a description of a device.
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Common Confusion
Spring guns are sometimes conflated with man-traps, but the terms are distinct. A man-trap is a mechanical device — typically spring-loaded jaws or a pit — designed to physically seize or injure a person without involving a firearm. Both are treated together in criminal statutes and common law because the underlying wrong is the same: deploying an unattended, indiscriminate instrument of serious bodily harm against any person who triggers it, regardless of guilt or innocence. Bouvier's groups them together for this reason. Researchers should check for both terms when surveying historical statutes, as a jurisdiction may criminalize one while its statutes are silent on the other, even though courts often apply the same principles to both.
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Why It Matters in Research
Spring guns occupy a well-defined corner of property law and criminal law, but the research terrain shifts considerably depending on the period and jurisdiction.
In nineteenth- and early twentieth-century sources, spring guns appear primarily as a criminal law problem — setting one was a statutory misdemeanor in England and in American jurisdictions that followed English common law. Bouvier cites the English authority (4 Steph. Com. 67) for the proposition that the offense requires intent that grievous bodily harm be inflicted. Researchers working in this period should look for the spring gun question in treatises on criminal law and in statutes addressing malicious injury or dangerous instrumentalities, not necessarily in property law materials.
The tort dimension became increasingly prominent in American law through the twentieth century. The central question — whether a landowner may use deadly force by mechanical means to protect property when the same force would be unlawful if applied directly by the owner's hand — became settled against the spring gun in most American jurisdictions. This shift was driven by the broader principle that human life takes precedence over property interests. Researchers tracing this evolution should be aware that the criminal and tort threads developed somewhat independently and that historical sources may address only one.
A significant trap in older sources: the intent requirement stated in Bouvier applies to criminal liability. Civil tort liability, as it developed, does not require that the owner specifically intend to harm a particular person — negligence or recklessness in setting the device can suffice. Do not import the criminal intent standard into a civil research question.
Because spring guns are now effectively prohibited in virtually all American jurisdictions, modern research questions tend to arise in three contexts: (1) historical property disputes, (2) constitutional challenges to statutes banning spring guns or analogous devices, and (3) products liability or personal injury cases involving commercial security devices that function similarly. For the third context, the encyclopedia entry on gun control legislation and federal/state constitutional challenges is the most useful starting point.
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Historical Dictionary Support
Bouvier's treatment is brief but precise. It frames the spring gun question entirely in criminal terms — misdemeanor liability for setting a device calculated to destroy human life or inflict grievous bodily harm, conditioned on intent. The citation to Stephens' Commentaries grounds the entry in English authority, which is appropriate given that American spring gun law descends directly from English statutory and common law.
What Bouvier does not address: the civil tort dimension, the defenses asserted by property owners (defense of property, implied consent of trespassers), or the rule — firmly established by the time of Bouvier's later editions — that a spring gun is unlawful even where a trespasser would have no right to complain of a similar wound inflicted by a person present on the property. The historical dictionaries generally treat this as a criminal law subject; the tort evolution must be traced in case reporters and property treatises rather than legal dictionaries of this period.
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Jurisdictional Note
Most American states have addressed spring guns either by statute or through controlling case law, with the dominant rule being that setting a spring gun to protect property — as opposed to a dwelling actually occupied and under immediate threat — is both tortious and criminal regardless of the trespasser's purpose. A handful of states have carved out limited exceptions for occupied dwellings. Researchers should not assume uniformity; statutes may use varying terminology including "spring gun," "booby trap," "man-trap," or "mechanical device."
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Encyclopedia Cross-Reference
Gun Control Legislation — Federal and State Constitutional Challenges (The Law Mind Constitutional Law Encyclopedia)
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