The nation’s highest court appeared to cast doubt on the viability of Mexico’s liability claims against the American gun industry Tuesday morning.

The Supreme Court heard oral arguments in the case Smith & Wesson v. Mexico. The case centers around the foreign government’s allegations that American gunmakers and distributors “aid and abet” cartel violence across the southern border by continuing to produce firearms that may be trafficked to criminals, even if they don’t knowingly sell those guns to the criminals. At issue is whether such claims are viable or if they are precluded by the Protection of Lawful Commerce in Arms Act (PLCAA), which shields the firearms industry from liability for third-party conduct.

Mexico faced tough questioning from the justices during the hearing. Even the liberal justices seemed suspicious that Mexico’s lawsuit could survive.

“I guess I’m just wondering whether the PLCAA statute itself is telling us that we don’t want the courts to be the ones to be crafting remedies that amount to regulation on this industry,” Justice Ketanji Brown Jackson said. “That was really the point of the entire thing. To the extent that we’re now reading an exception to allow the very thing that the statute seems to preclude, I’m concerned about that.”

The arguments arrived against the backdrop of deteriorating relations between the United States and Mexico. Both sides presented their cases to the justices on the same morning that sweeping new tariffs on Mexican goods imposed by President Donald Trump took effect. Trump has repeatedly accused the country of doing too little to stop the flow of illicit drugs and migration into the US. Mexico’s President, Claudia Sheinbaum, has retaliated with tariffs of her own against the US and has floated expanding the country’s lawsuit against American gunmakers.

The arguments also got to the heart of a conflict of visions between gun-control and gun-rights advocates over the propriety of assigning blame for illegal gun crime to legal gun businesses. A decision in the case will mark the first time that the High Court has weighed in on the contours of the PLCAA, even as it has come to play an outsized role in the political debate over guns in America over the last two decades.

Mexico sought to pierce the PLCAA when it first filed suit against Smith & Wesson and a half dozen of the biggest gunmakers in the country in 2021. Though the PLCAA generally blocks liability suits against the industry, it contains a number of exceptions, including instances in which gun businesses violate the law in the course of doing business. Seeking up to $10 billion in damages, Mexico alleges that Smith & Wesson is violating federal laws by providing its firearms to retailers that sell them to straw purchasers who traffic them into Mexico. The country also claims that American gunmakers knowingly produce firearms with “erasable serial numbers” and other designs that make them appealing to cartel members.

“The complaint details that Petitioners deliberately supplied the illegal Mexican market by selling guns through the small number of dealers that they know sell a large number of crime guns and who repeatedly sell in bulk to the cartel traffickers,” Catherine Stetson, the lawyer arguing for Mexico, said Tuesday. “The laws broken here are designed to keep guns out of criminals’ hands. Those violations put guns in criminals’ hands, and those criminals harmed Mexico.”

Noel Francisco, who represented the gun companies, said that Mexico’s theory of the US gun makers as the “proximate cause” of cartel violence is rendered impossible by the multi-step chain of custody their weapons go through before winding up at Mexican crime scenes. He said his clients are licensed manufacturers that simply produce legal firearms before selling them to licensed distributors, who then sell them to licensed retailers. Some of those licensed dealers may then sell them to straw buyers who illegally acquire them and later illegally transfer or smuggle them to Mexican criminal organizations, but he argued such a long series of discrete acts by independent actors–none of which were directly accused of crimes in Mexico’s complaint–does not amount to a criminal conspiracy perpetrated by the manufacturers.

“No case in history supports that theory,” Francisco said. “Indeed, if Mexico is right, then every law enforcement organization in America has missed the largest criminal conspiracy in history operating right under its nose.”

Multiple justices took aim at the lengthy chain of allegations. Justices Elana Kagan, Samuel Alito, and Amy Coney Barrett all separately commented on the fact that Mexico’s lawsuit does not name or target specific firearms dealers it claims are known for making illegal sales to weapons traffickers.

“You haven’t sued any of the retailers that were the most proximate cause of the harm,” Justice Barrett said. “And you haven’t identified them that I can tell in the complaint.”

Mexico’s design allegations did not fare much better before the justices. Stetson raised three examples of firearms manufactured by Colt—the Super El Jefe, the Super El Grito, and the Emiliano Zapata 1911—that she said were specifically designed for the Mexican market and to appeal to cartel members. However, Chief Justice John Roberts took issue with the idea that such designs indicated illicit intent.

“I mean, those are all things that are not illegal in any way,” he said. “There are some people who want the experience of shooting a particular type of gun because they find it more enjoyable than using a BB gun. And I just wonder exactly what the defendant, the manufacturer is supposed to do in that situation. You say, ‘No, he shouldn’t be marketing a particular legal firearm, because they’re going to go into Mexico at a higher percentage than than others.'”

Other justices raised practical issues with what it would mean to accept Mexico’s theory of liability.

Justice Brett Kavanaugh expressed “real concern” that ruling in Mexico’s favor could lead to “destructive effects” on different types of commerce beyond firearms. He posed hypotheticals about knife manufacturers selling their products in stores in regions where stabbings are prevalent or pharmaceutical manufacturers not providing their medicine to areas where prescription drug misuse is common.

“Is that where your theory of aiding and abetting leads, that you have to be kind of chasing, tracing everything down the chain and make sure we’re not selling in these places, or it’s not ending up in the places where it’s more likely to be misused?” he asked.

Though Mexico’s arguments seemed to find a cold reception Tuesday morning, there’s no guarantee that the Court will toss its case against the gunmakers. In fact, Mexico was successful at clearing initial legal hurdles in the lower courts. After a Massachusetts district judge tossed Mexico’s suit, the First Circuit Court of Appeals revived it last January in a ruling that said its arguments had successfully pierced the PLCAA’s liability shield.

Smith & Wesson swiftly appealed that decision, and the Court agreed to take the case last October. Though the case is unlikely to be decided on Second Amendment grounds, the company’s lawyer urged the Court to consider its decision’s implications on Americans’ constitutional rights regardless.

“At the end of the day, PLCAA is about protecting Second Amendment rights,” Francisco concluded Tuesday. “It’s not just about protecting the manufacturers, the distributors, and the retailers, but it’s protecting the right of every American to exercise their right under the Second Amendment to possess and bear firearms. That right is meaningless if there are no manufacturers, retailers, and distributors that provide them in the first place.”

The justices are likely to issue a ruling in the case by the end of June.