President Trump apparently wants to ban "bump stocks." Specifically, he has instructed Attorney General Jeff Sessions to have the Department of Justice interpret existing federal law to include bump stocks in the definition of a "machinegun." It may well be a good idea, but it's not clear the Department has the authority to do what the President wants.
The President first instructed the Justice Department to consider whether bump stocks can be regulated as fully automatic weapons last December. Pressed to take action on gun control, he now wants the Department to finish up and has called for the Department to propose "a rule banning all devices that turn legal weapons into machineguns."
The potential problem for any effort to ban bump stocks through unilateral executive action is existing federal law. 26 USC §5845(b) defines "machinegun" as follows:
any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger. The term shall also include the frame or receiver of any such weapon, any part designed and intended solely and exclusively, or combination of parts designed and intended, for use in converting a weapon into a machinegun, and any combination of parts from which a machinegun can be assembled if such parts are in the possession or under the control of a person.
At first it may seem that bump stocks can be covered because the definition expresslys include parts that can be used to turn a semi-automatic weapon into a fully automatic one -- but not so fast. The problem is that the language of the statute also specifies that what makes a weapon a machine gun is the ability to fire more than one shot automatically "by a single function of the trigger." This describes how fully automatic weapons work, but it does not describe how bump stocks operate.
While bump stocks facilitate rapid firing, they do so by rapidly and repeatedly engaging the trigger, not by enabling true automatic fire, a point Robert VerBruggen makes at NRO. In other words, a bump stock is not something that enables true automatic fire as defined by the statute. It is for this reason that bump stocks of the sort used by the Las Vegas shooter were not regulated as machineguns by the Obama Administration, which considered the question in 2013.
The Justice Department could try and argue that the relevant statutory text should be read functionally, rather than literally. That is, the government could say that this language should be understood to cover anything that simulates the rapid fire of an automatic weapon, even if it does so by the repeated function of the trigger. Further, the Department could argue that the intent of a bump stock is to "convert" a semi-automatic weapon into a fiarearm with automatic functionality, even if it does not actually "convert" a semi-automatic into one that can "shoot, automatically more than one shot . . . by a single function of the trigger." Finally, the Department could claim that while the trigger is repeatedly engaged with a bump stock, the shooter only acts to engage the trigger once. These arguments are clever, but perhaps too clever, as they take liberties with the relevant statutory text.
If the Justice Department goes forward, and the new interpretation is challenge, these arguments might hold up in federal court, but it's a calculated risk. If the Adminsitration truly wants to see bump stocks treated like those devices that do convert semi-automatics into machine guns, the safer and more direct route is to seek action by Congress.
Source : https://reason.com/volokh/2018/02/21/can-the-trump-administration-ban-bump-st673