The court ruled in Thompson Center Arms' favor in that the
carbine conversion kit did not constitute a short-barreled rifle, primarily because the kit contained both the stock and the 16-inch barrel.
Justice Scalia also noted that there is a warning carved on the stock telling the user to not attach the stock to the receiver when the 10-inch barrel is attached to the receiver or vice versa. This circumstance caused the court to apply the
rule of lenity since the NFA carries criminal penalties with it. This meant that ambiguous statutes are interpreted against the government. ==See also==