A Positive Law Framework for Firearm Bans

This guest post is based on a paper that was presented at the 2025 Firearms Law Works-In-Progress Conference and reflects the author’s views only. The Conference is held each year on a home-and-away basis with the University of Wyoming Firearms Research Center. This post also appears on the FRC's Forum. 

It is no secret that lower courts have struggled to resolve major Second Amendment challenges in the wake of New York State Rifle & Pistol Association v. Bruen.  Bruen’s history-and-tradition framework requires courts to spelunk through Founding- (and, maybe, Reconstruction) era history in search of legal principles with little guidance to ground the enterprise.  But not every Second Amendment question requires a resort to first principles.  When it comes to the constitutionality of weapon bans, the Supreme Court has already done the historical excavation.  In its landmark decision of District of Columbia v. Heller, the Court surveyed the history, extracted a principle, and crafted a binding rule of decision.  Based on a historical tradition of prohibiting dangerous and unusual weapons, the Court held that firearms in common use for a lawful purpose cannot constitutionally be banned.

Despite resolving the Bruen historical inquiry, common use has proven no more illuminating than other areas of Second Amendment doctrine.  That is because Heller is unclear on just what common use means.  The Supreme Court offered no framework for assessing a weapon’s commonality, threshold for what level of use suffices, or explanation for how its test would apply to evolving ownership trends.  Lower courts have found no greater success.  Many have simply avoided the common-use question by assuming without deciding that a weapon is in common use or by declaring that a challenged component is not an arm within the meaning of the Second Amendment.  Among the courts that have spoken on common use, they have generally coalesced around two competing visions.  The first approach turns the Second Amendment into a national popularity contest:  Once enough guns (proponents rarely say how many) fall into private hands, legislatures become constitutionally disabled from banning their use.  The second approach pigeonholes the Second Amendment to a narrow class of arms:  Only instances of active employment of a weapon in self-defense (again, proponents rarely say how often) count for the common use inquiry.

Down each road lies a hopeless Gordian Knot.  The problems with the popularity approach are myriad.  The inquiry is circular:  Successful bans are constitutional because they have prevented widespread ownership while a failure to regulate permanently disables future legislative action.  There is no principled line for what quantity of arms tips the common use scales.  The data proponents cite come predominantly from non-peer-reviewed interest groups.  And the evidence often lends itself to two competing tales.  To take but one example, is an AR-15 in common use because somewhere between 16 to 24.6 million Americans own AR-15-style rifles or because some 30 million platforms are in circulation?  Or is it not in common use because the rifle is owned by fewer than one-in-ten Americans and only twenty to thirty percent of gun owners?  As Justice Scalia colorfully quipped, the question is akin to asking “whether a particular line is longer than a particular rock is heavy.” 

The narrow approach fares little better.  Like its counterpart, it has no objective evidentiary metric and never offers a theory for how often a weapon must be actively employed in self-defense to make itself common.  Moreover, the test is built on at least two false premises.  First, that a firearm is only used for self-defense when it is actively employed in self-defense, as opposed to being owned in case such a need should arise.  Second, that self-defense is the only lawful purpose to which a firearm may be put, thus excluding other lawful activities such as hunting and marksmanship training.

Further straining the common use test are its ideological cleavages.  In general, Democratic-appointed judges take a narrow view of the Second Amendment and vote to uphold arms bans.  In contrast, Republican-appointed judges, particularly those appointed in recent years, take an expansive view of the Second Amendment and vote to strike down most arms bans.  With the common use test so malleable, it should perhaps come as no surprise that outcome-driven reasoning appears to be creeping into judicial decision making.

There is a better approach to common use, one familiar to our constitutional doctrine.  Common use should be treated as a question of positive law.  That is, courts should look to the municipal, state, and federal laws of America to assess whether a weapon is in common use for lawful purposes.  In effect, the common use test would police against outlier laws.  If a firearm can be lawfully used in a sufficient number of jurisdictions across time, it would be in common use.  But if a critical mass of jurisdictions prohibits lawful access, then the arm would not be in common use and those prohibitions would be constitutional.  Because a firearm can be lawfully owned in the absence of legislative action, the test would count the number of prohibitions on the statute books.

At first blush, it might seem odd to subject a constitutional right to the whims of disparate legislatures.  But across numerous constitutional rights, the Supreme Court has hewed to a similar tack:  Recognizing or expanding constitutional rights based on a stable national consensus, as measured by the positive law, in favor of a right.  Justice Kavanaugh has echoed a similar theme in his Second Amendment jurisprudence.  While on the D.C. Circuit, then-Judge Kavanaugh explained that Heller protected “traditional and common gun laws” while pushing back against “outlier . . . state legislative efforts.”  In Bruen, Justice Kavanaugh concurred to emphasize the outlier status of the New York gun permitting law held unconstitutional and to note that the shall-issue permitting schemes embraced by a majority of states were presumptively constitutional.  And in a recent statement respecting the denial of certiorari, Justice Kavanaugh indicated that bans on AR-15s are likely unconstitutional.  Why?  In part, because “AR-15s are lawful in 41 of the 50 States,” rendering the remaining nine prohibitions “outlier[s].”

A test that simply asks whether there is a stable national consensus or whether a law is an outlier is itself somewhat nebulous.  Fortunately, the Supreme Court’s rights jurisprudence offers a variety of rules to ground the inquiry.  First, the Court has typically required a stable supermajority of states to recognize a right before it is constitutionalized.  So a firearm should be considered in common use when it may consistently and lawfully be used in a supermajority of states.  Or put another way, if over twelve states prohibit a firearm, it would not be in common use.  Variations in municipal laws and state population may reasonably nudge the inquiry in either direction.  Second, in edge cases the tie should break in favor of lawful possession. This flows from Bruen’s admonition that conduct falling within the Second Amendment’s plain text is presumptively constitutional.  Third, federal law can establish a presumptive national consensus in either direction, but that consensus is defeasible by pushback from state and local jurisdictions.  Again, the rights arena is full of examples in which state practice contracts or expands a federal right.  Fourth, for new classes of arms that have not yet had the opportunity to enter common use, Heller’s dangerous and unusual test should control.  Under this approach, jurisdictions could ban new arms if those arms are shown to be unusually dangerous compared to the status quo ante.  Once that arm is of sufficient vintage, the test would revert to the default common use framework.  For example, a new rifle with only cosmetic changes in design would be sufficiently analogous to existing arms such that its regulation would be subject to the same rules as its most closely related relative.  But if a state could show that some feature of the rifle rendered it unusually dangerous compared to other rifles on the market, it could be prohibited.

Each of these principles will impose bright-line rules on the common use inquiry.  But their precise contours are not essential to embracing the broader methodological move of treating common use as a question of positive law.  Looking to positive law can objectify the common use inquiry, provide an easily administrable test, and limit outcome-oriented reasoning in Second Amendment jurisprudence.  It can break the logjam between judicial under enforcement and maximalism.  And it can return the focal point of debate back where it belongs:  With the People’s elected representatives.

A full version of the paper can be found here.