Declining to defer to a government agency on a statute with criminal applications, the U.S. Court of Appeals for the Sixth Circuit last week ruled that bump stocks are not machine gun parts, and that any determination otherwise—along with any subsequent criminal penalties—is the job of Congress. 

The Sixth Circuit's decision came just days before the U.S. Supreme Court agreed to reconsider its landmark 1984 ruling in Chevron v. Natural Resources Defense Council.