Miller was subject to two possible interpretations.  One, that the Second Amendment is an individual right, but that the right only extends to weapons commonly used in militias (the defendants in Miller were transporting sawed-off shotguns).  The second--broader--view of Miller is that the Amendment guarantees no rights to individuals at all, and the defendants lost the case as soon as it was obvious that they were not members of a state militia. 

In 2008, the U. S. Supreme Court, in District of Columbia vs. Heller, struck down a Washington, D.C. ban on individuals having handguns in their homes.  Writing for a 5 to 4 majority, Justice Scalia found the right to bear arms to be an individual right consistent with the overriding purpose of the 2nd Amendment, to maintain strong state militias.  Scalia wrote that it was essential that the operative clause be consistent with the prefatory clause, but that the prefatory clause did not limit the operative clause.  The Court easily found the D. C. law to violate the 2nd Amendment's command, but refused to announce a standard of review to apply in future challenges to gun regulations.  The Court did say that its decision should not "cast doubt" on laws restricting gun ownership of felons or the mentally ill, and that bands on especially dangerous or unusual weapons would most likely also be upheld.  In the 2008 presidential campaign, both major candidates said that they approved of the Court's decision.

Heller left open the question of whether the right to bear arms was enforceable against state regulation as well as against federal regulation?  In 1876, the Supreme Court said the right--if it existed--was enforceable only against the federal government, but there was a wholesale incorporation of Bill of Rights provisions into the 14th Amendment since then. In 2010, in the case of McDonald v Chicago, the U. S. Supreme Court held (5 to 4) that the 2nd Amendment right has been incorporated through the 14th Amendment's Due Process Clause and is fully enforceable against the states.  The Court, in an opinion written by Justice Alito, proceeded to strike down Chicago's gun regulation insofar as it prohibited the private possession in the home of handguns for self-defense.  Justice Thomas, concurring, would have held the right to bear arms to be a right protected by the Privileges and Immunities Clause of the 14th Amendment, an approach to applying Bill of Rights protections against the states first rejected in the 19th-century Slaughter-House Cases and never used since.