Washington DC - The US Supreme Court appeared poised on Tuesday to toss out a $10 billion lawsuit filed by Mexico accusing American gun manufacturers of fueling drug trafficking and violence.

Smith & Wesson and US gun distributor Interstate Arms are seeking dismissal of the Mexican government's suit, which has been winding its way through US courts since 2021.

Mexico, which is under mounting pressure from US President Donald Trump to curb drug trafficking, accuses the firearms makers of "aiding and abetting" illegal gun sales because they allegedly know that some of their products are being unlawfully sold to the drug cartels.

A federal judge tossed out the case in 2022 saying Mexico's claims failed to overcome the extensive protections offered by the Protection of Lawful Commerce in Arms Act (PLCAA), which was passed by Congress in 2005 and shields US gunmakers from liability for criminals misusing their products.

Justice Texas refugee resettlement charity takes aim at RFJ Jr. in lawsuit over funding freeze

An appeals court revived the case citing an exception to the law, and Smith & Wesson and Interstate Arms sought relief from the Supreme Court.

A majority of the justices on the conservative-dominated top US court appeared to side with the firearms companies during 90 minutes of oral arguments.

Noel Francisco, representing Smith & Wesson and Interstate Arms, said gun companies cannot be held accountable for the misuse of their products.

"If Mexico is right, then every law enforcement organization in America has missed the largest criminal conspiracy in history, operating right under their nose," Francisco said. "And Budweiser is liable for every accident caused by underage drinkers since it knows that teenagers will buy beer, drive drunk and crash."

Justice Brett Kavanaugh, a conservative, appeared sympathetic to this argument, questioning what consequences an expanded theory of aiding and abetting liability would have for the American economy.

"That's a real concern," Kavanaugh said. "Lots of sellers and manufacturers of ordinary products know that they're going to be misused by some subset of people."

Catherine Stetson, representing the Mexican government, was careful to steer the arguments away from any discussion of the Second Amendment to the US Constitution, which protects the rights of Americans to keep and bear arms.

"Mexico is not trying to legislate gun use in the United States," Stetson said.

She said up to 600,000 US guns are illegally trafficked into Mexico every year and the "manufacturers know that they are selling a dangerous product to specific rogue dealers who are selling to straw purchasers for the cartels."

Some gun companies are even "designing certain guns to target the Mexican market," she said, giving them Spanish names such as the Colt Super "El Jefe."

Francisco pushed back.

"The notion that selling a Spanish-named firearm is what gives rise to joint purpose with cartels under the aiding and abetting statute is as wrong as it is offensive," he said.

The Mexican government maintains that 70-90% of the weapons recovered at crime scenes in Mexico have been trafficked from the US.

Mexico tightly controls firearms sales, making them practically impossible to obtain legally.

Even so, drug-related violence has seen around 480,000 people killed in Mexico since the government deployed the army to combat trafficking in 2006, according to official figures.

The case comes against a backdrop of rising US-Mexico trade tensions. Trump imposed the new 25% tariffs on imports from Mexico on Tuesday, citing a lack of progress in stemming the flow of drugs such as fentanyl into the US.

Mexican President Claudia Sheinbaum vowed to hit back with retaliatory duties.