It's one of the most controversial passages of the Constitution. Allegedly, it's also one of the most obscure and unintelligible sections. The Second Amendment to the U.S. Constitution 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."

Prior to the Supreme Court's decision in District of Columbia v. Heller (2008), we were told for decades that the Second Amendment did not guarantee or even refer to an individual right. Based on the wording of United States v. Miller (1939), the theory was promulgated that the Second Amendment protected only State's rights to maintain organized militia. One problem with this curious interpretation is that States don't have rights, they have powers. But there's nothing new about twisting the truth into a pretzel so that it conforms to a dogmatic ideology. Some people still doggedly maintain that the Second Amendment does not refer to an individual right. Among these persons are some judges on the Seventh Circuit Court of Appeals. In clear defiance of the Supreme Court, the Seventh Circuit recently announced that "states, which are in charge of militias, should be allowed to decide when civilians can possess military-grade firearms."

Contrary to what some confused and unlettered judges think, the Second Amendment does indeed protect an individual right. Neither is it opaque or difficult to understand. A militia is "a citizen army," an entity that is most definitely distinct from a professional military. The Second Amendment becomes perfectly lucid when we understand that the "well regulated" militia spoken of in the Amendment is to be composed of a people who have right to keep and bear arms. The two clauses of the Second Amendment, the first which refers to a "militia," and the second which refers to "the people," cannot be separated and interpreted independently. For the Second Amendment to be intelligible the two clauses must be reconciled. Indeed, it is very difficult to assemble a militia from a people who have been disarmed.

The Second Amendment is not a radical innovation. Militia have a long history. The armed forces of the city-states of ancient Greece consisted mostly of ordinary citizens that banded together to defend themselves in time of common need. In Politics, Aristotle identified the right to keep and bear arms as synonymous with citizenship. He declared "those who possess arms are the citizens," and "the government should be confined to those who carry arms." Thus when we insist on the right to own guns, we are only asking for a right that has been ours by twenty-five hundred years of tradition in Western Civilization. To be deprived of our ancient and inalienable right is to be reduced to serfdom. It is an intolerable affront to a free people.

A militia can be governed and commanded when called to duty, but it is, nevertheless, not a body of professional soldiers. A "well regulated" militia is not one that is tightly controlled by a political administration. Rather, the term "well regulated" in the context of the Second Amendment means "well-trained" and thus efficient in its operation.

There are two advantages to defending a free state by means of a militia instead of a professional army. First, it's less expensive. Second, a militia has less allegiance to a tyrannical government than a select group of servicemen who rely upon that government for their livelihood. Thus the Second Amendment links the right to keep and bear arms to a "free state," not just a "state." The militia whose existence and continuance is guaranteed by the Second Amendment was intended by the Founding Fathers to serve as a safeguard against tyranny. In Federalist Paper No. 29, Alexander Hamilton explained that if the government ever tried to oppress the people with a standing army, that army would be countered by "a large body of citizens, little, if at all, inferior to them in discipline and the use of arms, who stand ready to defend their own rights and those of their fellow citizens."

What type of arms are citizens allowed to have? This is where the Supreme Court has largely failed us. In District of Columbia v. Heller (2008) the court decided that the Second Amendment protects weapons that are "in common use," while precluding "dangerous and unusual weapons." This is far from clear guidance. All weapons are "dangerous," and any firearm may appear "unusual" to a person who has no experience with guns.

An earlier Supreme Court case provides more sensible guidance on what type of weapons are protected by the Second Amendment. The despised United States v. Miller (1939) is commonly characterized as being the most recondite and obscure of all Second Amendment cases. But Miller constitutes the most useful guide in determining what types of weapons are protected by the Second Amendment. In Miller the Court noted that the militia consisted of "all males physically capable of acting in concert for the common defense," and that the Second Amendment "must be interpreted and applied... to assure the continuation and render possible the effectiveness" of this militia.

To be effective, the members of a militia must be well armed. Thus the quintessential weaponry protected by the Second Amendment consists of the arms that would ordinarily be possessed by an individual soldier in an infantry unit -- not weapons designed for defense from criminals or for shooting ducks. This means machine guns, mortars, and hand grenades. It excludes weapons of mass destruction such as large artillery pieces, poison gas, or aircraft. If this interpretation seems extreme, consider that our colonial militia possessed cannon. The Revolutionary War was initiated by the British attempt to seize cannon held by the militia at Concord.

We should not be too critical of the Heller decision crafted by the late Justice Scalia. It was decided on the most narrow of margins (by a 5:4 vote) and may have been the best compromise obtainable. Certainly, a decision that went the other way would have been devastating. Nevertheless, the wake of Heller has left case law in disarray. We have a judiciary largely composed of left-wing ideologues who detest the Second Amendment, find guns to be repulsive, and are almost completely ignorant regarding firearms and everything concerning them.

The Second Amendment states plainly that the right to keep and bear arms "shall not be infringed." But we have judges who are not only intent on infringing the right but curtailing it altogether. Some recent decisions contain comments that are asinine and embarrassingly ignorant. Among these is the moronic declaration by Fourth Circuit Judge Robert King that "assault weapons" (meaning semi-automatic rifles such as the AR-15) constitute "exceptionally lethal weapons of war." This must be news to the U.S. military, since they equip their infantry with select-fire rifles capable of fully automatic fire. After declaring the AR-15 to be "exceptionally lethal," Judge King then immediately contradicted himself by concluding that it has a "questionable utility for self-defense," seemingly oblivious to the fact that the utility of a weapon for self-defense is directly correlated with its lethality. In Judge King's opinion, the Second Amendment "affords no protection whatsoever" with regard to the what he terms "assault rifles and shotguns." One wonders what Judge King expects the militia described in the Second Amendment to equip themselves with -- wiffle bats and cap guns?

Judge King is not the only ignorant fool sitting on the Federal bench. In Friedman v. Highland Park (2015), Judge Frank Easterbrook ruled that the city of Highland Park could ban the possession of AR-15s and other common semi-automatic rifles because AR-15s were not in existence at the time the Second Amendment was written. Imagine the judiciary applying this logic to the First Amendment. The only means of expression protected would be materials printed on paper in shops where the print was set and inked by hand.

Another one of Judge Easterbrook's gems was the notation that his ruling was justified by the fact it "may increase the public's sense of safety." If this absurd rationale were applied in interpretation of the First Amendment, reading materials could be removed from your house if they placed your neighbor in a subjective state of fear or apprehension.

And who needs an AR-15? According to Judge Easterbrook, the city of Highland Park could ban semi-automatic rifles because the "ordinance leaves residents with many self-defense options." In other words, banning some books is all right so long as you're free to read others that are approved by the government. Such is the common practice in totalitarian regimes like Cuba, a place where Judge Easterbrook would no doubt be right at home.

The execrable decision crafted by Judge Easterbrook achieved the rare distinction of being expressly criticized by two Supreme Court justices. In a stinging dissent from the Court's failure to grant certiorari, Justices Thomas and Scalia noted that in the Highland Park case the Seventh Circuit did not follow the precedent and reasoning the Court outlined in Heller (2008). Thomas and Scalia concluded that if the judges on the Seventh Circuit Court were allowed to be arbiters of our rights then "the Second Amendment guarantees nothing."

There is not a single word in the U.S. Constitution regarding either abortion or gay marriage. Yet our ingenious federal judiciary has discovered that the Constitution guarantees both a right to kill babies and to sanction sodomy. Simultaneously, these cunning little tyrants blithely assure us that a right expressly guaranteed means nothing. If you steal a pack of cigarettes from a convenience store, you're going to be apprehended, arrested, and imprisoned. But if you strip three hundred million people of their most fundamental rights, you can sit smugly behind the bench under the blessing of judicial immunity and collect a hefty salary.

It is evident that we have a lot of work left to do. The best place to begin is to educate yourself. A good place to begin is with Stephen Halbrook's book, That Every Man Be Armed. Sanford Levinson's essay, "The Embarrassing Second Amendment", is also essential reading. If reading is not your style, get involved in politics. If you find politics distasteful, write out a check to the NRA or your favorite gun-rights organization. They need the money and will put it to good use. Please keep in mind: it's easier to write a check than it is to cross an icy Delaware River on Christmas Eve. If none of the preceding appeal to you, take someone shooting. No one can do everything, but everyone can do something.

Dr. Deming is professor of arts and sciences at the University of Oklahoma, and the author of Science and Technology in World History (McFarland, 2010, 2012, 2016).