The D.C.-Is-Not-a-State Argument:

The dissent in the D.C. Circuit Second Amendment case relied chiefly on the theory that, because D.C. is not a State, the Second Amendment — which reads “A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed” — “does not extend to [D.C.]” She argues that the reasoning of Miller v. United States so commanded:

[Miller held]:

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.

Id. at 178 (emphases added). Then, quoting Article I, § 8 of the
Constitution [specifically, the Militia Clauses -EV], the Court succinctly — but unambiguously — set
down its understanding of the Second Amendment: “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.” Id. Construing its two clauses together so that, as Miller declares, the right of the
people to keep and bear arms relates to those Militia whose continued vitality is required to safeguard the individual States,
I believe that, under Miller, the District is inescapably excluded
from the Second Amendment because it is not a State.

The trouble with this reasoning, it seems to me, is that Miller did not hold that the continued vitality of the Militia “is required to safeguard the individual States.” Miller talked about the Second Amendment’s being aimed at preserving the Militia, which Miller held “comprised all males physically capable of acting in concert for the common defense” (and who, at the Framing, “were expected to appear bearing arms supplied by themselves”). It said nothing about the Militia being required to safeguard the States. And the Militia as understood by Congress (from 1803 to the present) included the citizenry of D.C. as well.

Nor does the reference of a “a free State” exclude D.C.; as the majority points out, “a free State” likely meant what Madison originally wrote, “a free country” (“State” being a common term for country as well as for an individual state). The prefatory clause thus refers to protection of a free country — and it makes sense that the operative clause speaks of the right of “the people,” not of state citizens or even of the militia, because it too refers to the people living in this country, including in D.C. and in the territories (recall that the Northwest Territory was an important part of the 1791 United States).

This does leave an interesting question that neither opinion seemed to discuss: The Militia Clauses of article I, section 8 read:

Congress shall have Power …

To provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions;

To provide for organizing, arming, and disciplining, the Militia, and for governing such Part of them as may be employed in the Service of the United States, reserving to the States respectively, the Appointment of the Officers, and the Authority of training the Militia according to the discipline prescribed by Congress;

Does it follow that there may not constitutionally be any Officers or training for any militia in the District of Columbia and the Territories, since while Congress is free to organize, arm, and discipline the Militia everywhere, only the States may appoint officers and train the militia, and no State has jurisdiction in D.C. and the Territories? I doubt it; I would think, as did Congress in 1803, that the Militia — the armed citizenry — can exist and can be officered and trained throughout the breadth of the country. (Perhaps Congress’s power to officer and train the D.C. militia comes from the Seat of Government clause and the Territory Clause, which wouldn’t be limited by the “reserving to the States” proviso.) And if I’m right, then that’s evidence that the citizenry has indeed long been understood as having a right to have arms even in D.C. and the Territories.