When the Supreme Court of the United States (SCOTUS) refused to hear a case challenging an “assault weapons” ban in a Chicago suburb on December 7, Justice Clarence Thomas dissented and revealed his belief that Supreme Court precedents would have shown AR-15s—and similar rifles—are protected by the Second Amendment.

Justice Antonin Scalia joined Thomas in dissent.

SCOTUS does not explain why it takes up some cases and refuses others, but Thomas and Scalia equated the court’s refusal to hear the case with “abdicating… responsibility to enforce the constitutional right to keep and bear arms.”

Thomas wrote, “Roughly five million Americans own AR-15 style semiautomatic rifles.” And he explained that the “overwhelming majority of citizens who own and use such rifles do so for lawful purposes, including self-defense and target shooting. Under our precedents that is all that is needed for citizens to have a right under the Second Amendment to keep such weapons.”

When Thomas says that SCOTUS’s precedents demonstrate that the commonality of the AR-15 is evidence of its protections under the Second Amendment, he is alluding to the court’s decision in District of Columbia v Heller (2008). There the court explained that the test of commonality is one of the chief means of ascertaining which weapons are protected for the people’s possession.

According to Heller, “the sorts of weapons protected” by the Second Amendment when it was written were those “in common use at the time.” And this has been true throughout the 224 years that have passed since the Second Amendment’s ratification. It means the guns “in common use” among the citizenry are the guns protected by the Bill of Rights. And with five million AR-15 owners in America today, those rifles are certainly “in common use” among the citizenry, and therefore protected.

Certain other weapons are easily recognized as not “in common use”—shoulder-fired rockets, rocket propelled grenades, etc.—and are not covered by the precedents that exist under the Second Amendment.

Follow AWR Hawkins on Twitter: @AWRHawkins. Reach him directly at awrhawkins@breitbart.com.