United States v. Miller (Second Amendment Case Law Review)
"Certainly it is not within judicial notice that this weapon is any part of the ordinary military equipment or that its use could contribute to the common defense"
Key Principle: A sawed off shotgun is distinguishable from other firearms, and therefore may be regulated, because it is not "ordinary equipment" and may not "contribute to the common defense."
United States vs. Miller is an old Supreme Court case, stemming from 1939, but there would not be another DIRECT Second Amendment case for almost 7 decades in the 2008 case of District of Columbia vs Heller (covered previously). It's one that's cited by both sides, as anti-2A forces say it authorizes regulation of weapons, while the pro-2A position states that it broadly protects weapons that are common military equipment or that contribute to the common defense.
The background of the case stems from the National Firearm Act, passed after the St. Valentines Day Massacre and other Chicago Gang violence, which required certain types of firearms, such as fully automatic firearms and short-barreled rifles and shotguns, to be registered with the Miscellaneous Tax Unit, which eventually became the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). The defendants, Jack Miller and Frank Layton, were charged with unlawfully and feloniously transporting an unregistered double barrel 12-gauge shot gun with a less than 18 inch-long barrel from Oklahoma to Arkansas, in violation of the National Firearms Act. However, the defendants argued that the Firearms Act violated the Second Amendment.
The 1939 Supreme Court ultimately decided that the National Firearms Act did not violate the Second Amendment of the US Constitution and was not unconstitutional as an invasion of the reserved power of the states. The reasoned that because they were not presented with any evidence showing that the possession of use of a shotgun having a barrel of less than eighteen inches in length at this time had a reasonable relationship to the preservation or efficiency of a well regulated militia. Therefore, it was not within judicial notice that the weapon was, at the time, part of ordinary military equipment or that its use would contribute to the common defense. Justice Reynold's said that the effectiveness of the militia was an obvious purpose for the Second Amendment, and therefore, regulations must be applied with that view in mind.
We then fast forward and apply this, seemingly mixed, case law to today, specifically towards challenges to firearms labelled as assault weapons. This is precisely the position taken by a California Judge Roger T. Benitez in the case of (ironically) Miller vs Bonta, Attorney General of California, where Judge Benitez held that California's AR-15 ban was unconstitutional, citing BOTH DC v. Heller and US v. Miller in his ruling. He states that the AR-15 is the perfect weapon both for home defense AND homeland defense (i.e. common defense) and is therefore the quintessential weapon protected by the Second Amendment.