U.S. Supreme Court building on April 23, 2019.

In a case with potential implications for all regulated industries, gun rights advocates are asking the U.S. Supreme Court to reverse a federal appellate court decision applying deference to the Bureau of Alcohol, Tobacco, Firearms and Explosives' rule banning bump-stock devices.

In Guedes v. ATF, a group of bump-stock owners and Second Amendment organizations argue that the U.S. Court of Appeals for the D.C. Circuit incorrectly applied so-called Chevron deference to the agency's interpretation of "machinegun" in two criminal statutes: the National Firearms Act of 1934 and the Gun Control Act of 1968.

The petition for review, filed by Erik Jaffe of Washington, D.C.'s Schaerr Jaffe, contends that the circuit court's 2-1 decision in April "stretches the [Chevron] doctrine beyond its breaking point." The Chevron doctrine stemmed from the Supreme Court ruling in Chevron U.S.A. v. Natural Resources Defense Council, which established a two-part framework for evaluating an agency's interpretation of a statute.

"Although the agency had never sought and expressly eschewed Chevron deference for its interpretation of a central element of a criminal statute, the panel majority held that the statutory definition of 'machinegun' was ambiguous and that deference, rather than the rule of lenity, applied and could not be waived by the government," wrote Jaffe in the petition.

The rule of lenity, according to the Supreme Court, requires that "when there are two rational readings of a criminal statute, one harsher than the other, [the court is] to choose the harsher only when Congress has spoken in clear and definite language." Jaffe argues, "There certainly is no clear statement here directing or specifically authorizing ATF to adopt the harsher version of ambiguous definitions of crimes."

The petition urges the justices either to correct the D.C. Circuit decision or, if necessary, to overrule Chevron.

Reed Smith partner James Segroves, who has been following the case, said, "The question whether a federal agency should receive Chevron deference when interpreting a criminal statute is of potential significance to virtually all regulated industries, including the health care and life sciences industries." The D.C. Circuit decisions and others, he said, "make it a closer question."

Interest in regulating bump-stocks skyrocketed following the October 2017 mass shooting in Las Vegas where the shooter had attached one to his semi-automatic firearms in order to get it to fire like an automatic weapon. The bureau issued its final rule banning the devices in December 2018, with an effective date of March 26, 2019.

The Guedes plaintiffs argued in the district court that the bureau lacked authority to promulgate the rule and that violated the Administrative Procedure Act. None of the parties, including the government, advocated application of Chevron. The district court refused to issue a preliminary injunction against the rule, and the D.C. Circuit, in a divided per curiam opinion, affirmed.

Judge Karen Henderson dissented, saying Chevron cannot be applied to criminal laws. She also argued that the bureau had impermissibly expanded the definition of "machinegun" in the two federal gun laws.