The Mexican government has sued U.S. gun manufacturers, blaming them for crime and cartel violence south of the border. A federal appeals court allowed the case to move forward, so Republican members of the U.S. Senate and House of Representatives are urging the Supreme Court to defend American sovereignty.

“Mexico is trying to impose its own interpretation of American law on American businesses, and in the process, erode American sovereignty and threaten the Second Amendment,” Sen. Ted Cruz, R-Texas, who led the effort, said in a statement Friday.

“As if facilitating the border crisis was not enough proof on its own, the current government in Mexico has shown a complete disregard for our laws, our Constitution, and our Second Amendment,” Cruz added. “The Supreme Court should defend our Constitution and American sovereignty by taking this appeal and unanimously reversing the First Circuit’s disastrous decision.”

In January, the U.S. Court of Appeals for the 1st Circuit ruled that Mexico’s lawsuit against U.S. gunmakers could go forward. Mexico had sued Smith & Wesson, Barrett Firearms, Beretta, Colt, Glock, and others for allegedly engaging in practices that facilitate illegal arms trafficking to Mexico.

Among other things, Mexico faulted the companies for forgoing “safety features” like “allowing only recognized users to fire [a] weapon,” for making serial numbers that can be easily removed, and for designing their firearms as “military-grade weapons.” While Mexico has strict gun laws and has just one legal firearms store in the entire country, cartels and other criminals illegally import firearms from the U.S.

Mexico filed its claim in federal court in Massachusetts, alleging harms in common law for the companies’ alleged abetting of cartel violence in Mexico. The district court denied Mexico’s claims, finding that the Protection of Lawful Commerce in Arms Act, which President George W. Bush signed into law in 2005, forbids a foreign government from suing U.S. companies on those grounds.

The 1st Circuit reversed, however, ruling that Mexico had successfully claimed that the law does not apply, since it does not protect “an action in which a manufacturer or seller of a qualified product knowingly violated a State or Federal statute applicable to the sale or marketing of the product, and the violation was a proximate cause of the harm for which relief is sought.”

The 1st Circuit held that “Mexico’s complaint adequately alleges that defendants have been aiding and abetting the sale of firearms by dealers in knowing violation of relevant state and federal laws.” The court therefore ruled that the case could proceed.

The manufacturers appealed to the U.S. Supreme Court, which has yet to decide whether to take up the case.

Cruz, who clerked at the Supreme Court in the 1990s before serving as Texas solicitor general in the 2000s and later becoming a U.S. senator in 2013, led 12 other senators and 14 representatives in filing an amicus brief urging the Supreme Court to reverse the 1st Circuit’s ruling.

“The foreign nation of Mexico has filed a lawsuit that attempts to use the federal courts to advance a theory of liability for lawful American businesses that would vitiate a constitutional right and do so in direct conflict with a law Congress passed precisely to prevent such liability,” the brief states. “The Second Amendment to the United States Constitution ensures the right to keep and bear arms for law-abiding and peaceable American citizens, but it would be impossible to exercise that right if a citizen could not lawfully purchase a firearm because the firearms industry had become insolvent.”

“Congress passed the Protection of Lawful Commerce in Arms Act to prevent such an outcome by placing firearm manufacturers on equal footing with other American manufacturers,” the brief adds. “Under the Act, so long as a firearm is properly made and properly transferred into commercial channels, a manufacturer is generally not liable if a criminal later misuses that firearm in the commission of a crime.”

Twelve Republican senators joined Cruz on the brief: Florida’s Rick Scott, Indiana’s Mike Braun, Kansas’ Roger Marshall, Montana’s Steve Daines, North Carolina’s Ted Budd and Thom Tillis, North Dakota’s Kevin Cramer, South Carolina’s Lindsey Graham, South Dakota’s John Thune, Tennessee’s Marsha Blackburn, Texas’ John Cornyn, and Utah’s Mike Lee. Rep. Darrell Issa, R-Calif., led 13 House members in joining the brief.

“It is vitally important that the Supreme Court stand up for the Second Amendment rights of Americans and affirm federal law protecting gun manufacturers from liability for crimes committed with lawfully manufactured firearms,” Lee said. “No foreign country should be able to interfere with the U.S. Constitution, and we should protect America’s sovereignty. I expect the Supreme Court will do so.”

“The Supreme Court must act to overturn the 1st Circuit’s decision and protect American sovereignty from this blatant political stunt from Mexico,” Tillis said. “Rather than solving the drug and crime problem plaguing their country, Mexico is blaming the United States for problems it should have solved a long time ago.”