You can find just about any kind of restaurant imaginable in our nation’s capital, but what you won’t find, no matter how hard you look, is a gun store. D.C. residents who want to buy guns, like Tracey and Andrew Hanson, have to leave the district to get them. D.C. law specifically allows residents to buy firearms from outside the District.

So the Hansons visited Frederic Mance, a federally licensed gun dealer in Texas. D.C. law had no problem with the Hansons buying a gun from Mance, and the law of Texas allowed Mance to sell to the Hansons. The Hansons agreed to buy handguns from Mance in what would be an otherwise entirely lawful transaction, but there was a problem: the federal government (of course).

Federal law categorically forbids firearms dealers from selling handguns to anyone not a resident of the state in which the dealer does business. The purported justification for this restriction is that the government doesn’t believe licensed dealers can handle complying with the laws of the purchaser’s state—even though they are required to do just that should the customer want something like a bolt-action rifle, shotgun, or even (heavily restricted) machine guns.

Mance, the Hansons, and several others sued the federal government in Texas, arguing that the interstate handgun-transfer ban violated their Second Amendment right to bear arms and Fifth Amendment right to equal protection. The district court agreed that the law was unconstitutional, but when the case came to the U.S. Court of Appeals for the Fifth Circuit, a closely divided court found for the government, over strong dissent. The plaintiffs now appeal their case to the Supreme Court, hoping our nation’s highest court will finally step in and clarify how laws are to be evaluated under the Second Amendment—something the justices have avoided doing since declaring in D.C. v. Heller (2008) that there is indeed an individual right to keep and bear arms.

Federal law has put the national firearms market into an irrational state. Dealers are trusted to follow the law of multiple states when selling long guns, but are categorically forbidden from doing the same with the most common arms in the country. It regulates the interstate arms trade as if the Founders hadn’t been driven to war by embargoes on trading guns, and exclusively targets the arms which Americans—and the Supreme Court—have indicated are the most crucial for self-defense.

Because the right to armed self-defense is fundamental and should not be given “second class” treatment, Cato has filed an amicus brief urging the Supreme Court to hear the Mances’ case. In an area of the law where the circuits diverge substantially on how to treat an important civil right, the Court needs to step in and help set the course. This case is an ideal vehicle in which to do it, as its resolution would not directly disrupt the nation’s diverse tapestry of gun laws, but instead help equip lower courts with the tools they need to properly map the metes and bounds of the Second Amendment.

The Supreme Court will decide whether to take up Mance v. Whitaker later this winter.