Criminal Law, Pages 168–175

Staples v. United States

Supreme Court of the United States, 1994


Prosecution bought an AR-15 that had been modified to fire fully automatically. He was not aware of this change and had not tried to do so. BATF agents seized the weapon, and defendant was indicted for unlawful possession of an unregistered machinegun. The statute violated does not specify what if any mens rea is required for violating it.

Procedural History:

District court charged the jury that the government did not need to prove that the defendant knew every characteristic of his weapon that made it illegal, only that he knew that it was "a dangerous device of a type as would alert one to the likelihood of regulation." Defendant was convicted and sentenced to five years' probation and a $5,000 fine.


Does the statute require proof that a defendant knew of the characteristics of his weapon that made it a "firearm" under the act?


Generally, crimes require a mens rea to be present. Strict liability offenses are disfavored and require an indication of congressional intent to establish them as such.


The government claims that this statute concerns a "public welfare" offense, which are often strict liability offenses. But these only apply in limited circumstances with dangerous items defendants knew they were handling.

The government claims that this is analogous to declaring that prosecuting one for possessing grenades does not require him to know that they are unregistered. He assumedly would still know that they are grenades which are very dangerous regardless of whether they are registered or not and fall under the statutory definition of a "firearm." This is different than when one, like defendant, claims that he did not know that his firearm was a "firearm" under the statute.

Normal firearms have a long tradition of lawful ownership, quite unlike grenades. Even dangerous items can be so commonplace and generally available that they would not alert individual to the likelihood strict regulation. Considering firearms "dangerous" devices because of the regulations so commonly place thereupon could also lead to cars being similarly classified.

Such a strict penalty also support this not being a strict liability offense. It would undoubtedly punish innocent people who unknowingly possess illegal items and would face harsh penalties for it.


Yes, the statute requires that defendant was aware that his gun was a machinegun. Reversed and remanded.

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