On March 30, 1939 the Supreme Court heard the case. Attorneys for the United States argued four points:Source: Wikipedia
The National Firearms Act [NFA] is intended as a revenue-collecting measure and therefore within the authority of the Department of the Treasury.
On May 15, 1939 the Supreme Court, in a unanimous opinion by Justice McReynolds, reversed and remanded the District Court decision. The Supreme Court declared that no conflict between the NFA and the Second Amendment had been established, writing:
The defendants transported the shotgun from Oklahoma to Arkansas, and therefore used it in interstate commerce. The Second Amendment protects only the ownership of military-type weapons appropriate for use in an organized militia.
The "double barrel 12-gauge Stevens shotgun having a barrel less than 18 inches in length, bearing identification number 76230" was never used in any militia organization. Neither the defendants nor their legal counsel appeared at the U.S. Supreme Court.
In the absence of any evidence tending to show that possession or use of a 'shotgun having a barrel of less than eighteen inches in length' at this time has some reasonable relationship to the preservation or efficiency of a well regulated militia, we cannot say that the Second Amendment guarantees the right to keep and bear such an instrument.
Describing the constitutional authority under which Congress could call forth state militia, the Court stated:
With obvious purpose to assure the continuation and render possible the effectiveness of such forces the declaration and guarantee of the Second Amendment were made. It must be interpreted and applied with that end in view. The Court also looked to historical sources to explain the meaning of "militia" as set down by the authors of the Constitution:
The signification attributed to the term Militia appears from the debates in the Convention, the history and legislation of Colonies and States, and the writings of approved commentators. These show plainly enough that the Militia comprised all males physically capable of acting in concert for the common defense. 'A body of citizens enrolled for military discipline.' And further, that ordinarily when called for service these men were expected to appear bearing arms supplied by themselves and of the kind in common use at the time.
So what triggered all of this interest today in a year and a half old thread?