Miller argued that the Second Amendment to the Constitution of the United States provides: A well regulated militia being necessary to the security of a free state, the right of people to keep and bear arms, shall not be infringed; that the said National Firearms Act is in violation and contrary to said Second Amendment and particularly as charging a crime against these said defendants, is unconstitutional and therefore does not state facts sufficient to constitute a crime under the statutes of the United States.
The SCOTUS, after hearing only the government's arguments (Miller's attorneys were not present), determined that, without evidence to the contrary, a sawed-off shotgun was not a military-style weapon, and, therefore, was not protected by the 2nd Amendment. The court did not challenge the notion that Miller was in the militia, even though he clearly was a private citizen with no connection to the National Guard..
Let's assume the Miller ruling was correct. If so, then all of us are in the militia, and all of us have a right to keep and bear an M16.
I'll buy that...