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With each new mass shooting, the debate over gun control becomes more angry—and more predictable. One constant is the battle over the meaning of the Second Amendment to the U.S. Constitution: “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.” Gun control proponents argue that the Amendment is purely about the maintenance of state militias (the first 13 words); their opponents see an unfettered right to bear arms (the next 14).

The Constitution was created by the states. The delegates to the Constitutional Convention were appointed by their states’ legislatures, and were for the most part vigorous supporters of state prerogatives. They were only willing to grant the national government those powers, primarily for defense and foreign relations, that their experience told them had to be centralized; all other governmental powers were to remain with the states.

As part of the ratification package, Congress added ten Amendments—the Bill of Rights—to further limit the powers of the federal government. Today we see the Bill of Rights as a guarantee of individual liberties, but those first amendments only guaranteed rights against encroachment by the national government; the states were left free to encroach as they saw fit. For example, the First Amendment prevents Congress from establishing a religion, but ten states retained such establishments, which no one then thought unconstitutional.

Against this background, the central thrust of the Second Amendment is clear: The states, jealous of their power to maintain militias, wanted to prevent their newly-created federal government undermining that power by limiting individual possession of firearms. The Second Amendment thus left the regulation of firearms to the states.

For the late 18th century, citizen militias were the preferred alternative to a standing army, which was seen as a potential instrument of despotism. But subsequent experience with militias was not encouraging, and it has been some time since any state has maintained one. Instead, the states have relied on professional police forces, which are not generally equipped with military-type weapons, to maintain public order.

State militias have proved so unnecessary that the federal government has not hesitated to infringe the right to bear arms where military-type weapons are involved. The National Firearms Act (1934) effectively prevents private citizens from owning automatic weapons such as machine and submachine guns that would be appropriate for a military force. The Supreme Court has never ruled on the constitutionality of these limits, though in 1939 the Court upheld the Act as applied to sawed-off shotguns on the ground that such weapons had no military use. Regardless of the Second Amendment, few today question the federal government’s ability to limit private ownership of tanks, artillery, machine guns, and other implements of military violence.

So how did the Second Amendment come to be interpreted as conferring an individual right to bear arms free of state control? The answer lies in the doctrine of “incorporation.”

The most important fact about our Constitution—which liberals and conservatives alike generally refuse to countenance—is that it is a totally inadequate framework for the modern American republic: Few of us would want to live under the government it describes. In particular, the Constitution does not protect those freedoms we now take for granted—of speech, assembly, and religion, from unreasonable searches and seizures, and so forth—against state impingement. That we have the freedoms we want is due to a long history of the Supreme Court reading the Constitution in ways its authors never contemplated. A crucial tool in this judicial rejiggering is the 14th Amendment. Adopted in 1868, it provides that no state can “deprive any person of life, liberty, or property, without due process of law”—the Due Process Clause.

The most natural reading of the Due Process Clause would make it to be about appropriate procedure: A state can’t execute or jail you, or take your property, without a fair proceeding. That reading is powerfully supported by the Clause’s history.

The Fifth Amendment to the Constitution—part of the original Bill of Rights—contains its own due process clause, a near identical restriction on the federal government. But the Fifth Amendment’s due process clause is embedded in a list of procedural requirements—grand jury indictment for prosecution of capital or “otherwise infamous” crimes, no double jeopardy, the right not to be a witness against oneself, and just compensation for taking property for public use. The 14th Amendment simply lifted the “deprive life, liberty, or property, without due process of law” phrase, with no suggestion that the words would mean something different when torn from their procedural context.

It wasn’t long, however, before the Supreme Court adopted the view that the Due Process Clause was also about substance, which substance was provided by the Bill of Rights itself. The Due Process Clause was held to “incorporate” into state law some of the liberties guaranteed by the Bill of Rights. Thus, for example, a state could not abridge freedom of speech because the 14th Amendment incorporated the First Amendment’s free speech guaranty. Gradually, the courts found more and more of the Bill of Rights to be so incorporated.

The Supreme Court has not held, however, that all of the rights guaranteed in the Bill of Rights are incorporated, relying instead on the theory of “selective” incorporation. This theory, however, seems to require that the authors of the 14th Amendment knew which parts of the Bill of Rights were to be incorporated but neglected to tell anyone. Thus, over time, the courts have purported to tease out the meaning of the Due Process Clause by asking which parts of the Bill of Rights involve “fundamental” liberties. This explains why in 2010, 142 years after ratification of the 14th Amendment, a four-justice plurality in McDonald v. Chicago discovered that the Due Process Clause incorporated the Second Amendment’s right to bear arms.

McDonald, while supposedly establishing a general “right to bear arms,” is almost entirely devoted to a more limited right—the right to keep a firearm at home for self-defense. Unfortunately, incorporation is an all-or-nothing business, so the justices found themselves propounding a sweeping individual right, which they then tried to walk back by ad hoc rationalizing: The right to keep and bear arms is not “a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose.” The Court stated that its holding would not overturn state laws outlawing the possession of firearms by felons and the mentally ill, or the carrying of firearms in sensitive places such as schools and government buildings, or that imposed conditions and qualifications on commercial arms sales. Clearly, McDonald did not settle the limits of the right to bear arms.

The Court’s backing and filling, as it attempted to reconcile a broad right to bear arms with sensible limits on that right, carries a kicker. The Court reaffirmed earlier holdings that “incorporated Bill of Rights protections are all to be enforced against the States under the 14th Amendment according to the same standards that protect those personal rights against federal encroachment.” It seems to follow that any state regulations the Court views as acceptable could also be imposed by the federal government. For example, if it’s reasonable for a state to ban assault weapons, then the federal government can also enact such a ban, which would apply to all the states. The Second Amendment has thus been stood on its head: Originally intended to allow the states to regulate firearms without federal interference, it is now held to limit the states’ regulatory powers while granting a broad role for federal oversight.

If Congress can somehow manage to pass gun control legislation, what will the Supreme Court hold? Much depends on the Court’s future composition. But as a consequence of its ruling in McDonald, the current Court’s incorporation of the Second Amendment may have created a new Constitutional opening for federal regulation.

Howard Darmstadter

Howard Darmstadter is a retired lawyer and philosophy professor who lives in Stamford, Connecticut and writes on law, philosophy, and public policy.