Had Miller and Layton gone to trial, they would have been able to argue the suitability of a short-barreled shotgun before a jury. That the Supreme Court failed to take judicial notice that such an instrument was or was not suitable for military use meant that the issue had to be determined as a factual matter in trial court.
The government's end-run around this was rather clever, and a number of lower courts have gone along with it, citing the syllabus from Miller as opposed to the decision itself. The bottom line (literally) on Miller was that the case was remanded to trial court for further proceedings. Such proceedings would have included factual matters raised by the Supreme Court. The syllabus omits this little detail, however, and so do the courts that cite it.
Congress declared the less than 18" shotgun to be a weapon of criminals and required a tax stamp.
Are you saying that some jury of 12 citizens can tell the entire Congress that they're wrong, the shotgun is indeed useful to a militia, Congress' law is therefore unconstitutional, and the defendant is free?
Shouldn't the state be bring the case to the U.S. Supreme Court? Shouldn't the state be the one saying that Congress, by requiring a tax stamp on a weapon THEY consider useful to THEIR state militia, is a violation of the second amendment?
How can we allow a jury of 12 citizens to determine which weapons are suitable for the militia of some state? That's dangerous if you ask me.