Reading the opinion is helpful, as there is a lot of stuff in it that gives everything context. The link I provided previously contains a comprehensive collection of primary documents that relate to this case.
Here's the bottom line of the opinion:
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. 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. Aymette v. State, 2 Humphreys (Tenn.) 154, 158.
It is important to know that at the time the court made this ruling, the accused was already dead, and his lawyer did not see fit to argue the case before the court, so there was no rebuttal made to the government's case. If you read the above carefully, you'll see that the reason the court ruled against Miller was because no evidence had been submitted to the court showing that a sawed off shotgun was useful as a military weapon. (Despite the fact they'd been used extensively in WWI - hence the name "trench gun".) It is entirely reasonable to assume, that given the court's reasoning, that they'd have O.K'd the firearm had they been aware of its use. Interestingly, this cuts directly against many gun-grabbers and their fellow travellers' claims that full-auto machine guns and "assault weapons" aren't protected.
I personally disagree with part of the court's reasoning, in that I think just about any firearm you'd care to name is covered by the Second Amendment because they can all be put to military and personal use regardless of what they might initially have been designed or marketed for. If you read the opinion, you'll note that though they spoke of 'militia weapons', whether or not Mr. Miller was a part of a formal militia group was not at issue.
From a legal standpoint, it might have been reasonable for the Supreme Court to take "judicial notice" of the usefulness of a short-barreled shotgun. That might have allowed them to unequivocally uphold the lower court's dismissal.
But the legal matter before the court had to do with deciding how the scope of the Second Amendment would be determined, given that the scope was other than as worded in the Second Amendment; that is, that all arms are protected from infringement.
It would certainly NOT be the case that the Supreme Court would expect every case involving each particular type of arm to come before the Court. The Supreme Court, as a matter of law, would be expected to detail how the lower courts were to make such determinations.
I’ll read it, thanks