A US appeals court has ruled that a $10bn lawsuit filed by Mexico against US gun manufacturers can go ahead, reviving a long-running legal battle.
Mexico's government argues that the "flood" of illegal guns across the border is a result of "deliberate" business practices by the US gunmakers.
A lower court had dismissed the case in late 2022, prompting an appeal from the Mexican government.
The gun industry's trade association has denied any wrongdoing.
Among the companies named in the lawsuit are Smith & Wesson, Glock, Beretta, Barrett, Sturm and Ruger.
Mexican authorities allege that tens of thousands of US-manufactured guns are trafficked south across the border each year, providing drug cartels with easy access to massive arsenals used to fight each other and the Mexican government. Some estimates put the total at over half a million weapons each year.
More than 30,000 people were murdered last year in Mexico, which has extremely restrictive gun laws. The country is home to only one gun shop, housed in a Mexico City military complex.
The lawsuit, which was first filed in 2021 in a federal courthouse in Massachusetts - where several of the companies are based - argued that the manufacturers knew that guns were being sold to traffickers fuelling violence in the country.
But in 2022 a US federal judge dismissed the case on the grounds that the gun manufacturers were protected by a 2005 law known as the Protection of Lawful Commerce in Arms Act. The law, also known as the PLCAA, shields gunmakers from damages "resulting from the criminal or unlawful misuse" of their products.
Mexico's government swiftly appealed, arguing that the law only applies to injuries that take place in the US and does not protect the defendants - which include seven manufacturers and one distributor - from liability.
On Monday, a US appeals court ruled that the Mexican lawsuit "plausibly alleges a type of claim that is statutorily exempt" from the PCLAA, which only covers lawful gun sales.
Mexican and gun control advocates in the US quickly claimed the ruling as a victory, with Mexican Foreign Minister Alicia Bárcena calling it "great news" on X, the platform formerly known as Twitter.
In a statement, Jon Lowy, the president of Global Action on Gun Violence - who serves as Mexico's co-counsel on the case - said that the ruling is a "huge step forward in holding the gun industry accountable for its contribution to gun violence, and in stopping the flood of trafficked guns to the cartels."
"Not only did the Court recognize the right of another country to sue U.S. gun companies, it also pierced the unfair legal shield that gun companies have been hiding behind since 2005," he added.
Larry Keane, the senior vice-president and general counsel of the National Shooting Sports Foundation, a trade group that represents the US firearms industry, defended the manufacturers.
"Mexico should spend its time enforcing its own laws [and] bring Mexican criminals to justice in Mexican courtrooms, instead of scapegoating the firearm industry for their unwillingness to protect Mexican citizens," he wrote on X.
