Washington DC - The US Supreme Court on Thursday dismissed a $10 billion lawsuit by the Mexican government accusing American gun manufacturers of fueling drug cartel violence.

In a unanimous 9-0 opinion, the top court said a federal law – the Protection of Lawful Commerce in Arms Act (PLCAA) – shields the gun makers from liability.

"Mexico's lead claim – that the manufacturers elect to sell guns to, among others, known rogue dealers – fails to clear that bar," said Justice Elena Kagan, the author of the opinion.

"Mexico's complaint does not plausibly allege that the defendant manufacturers aided and abetted gun dealers' unlawful sales of firearms to Mexican traffickers."

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Gun maker Smith & Wesson and gun distributor Interstate Arms had sought 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 President Donald Trump to curb drug trafficking, had accused the firearms makers of "aiding and abetting" illegal gun sales because they allegedly know that some of their products were being unlawfully sold to the drug cartels.

A federal judge tossed out the case in 2022, saying Mexico's claims failed to overcome the protection of the PLCAA, which was passed by Congress in 2005 and shields US gunmakers from liability for criminals misusing their products.

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 more than 90 minutes of oral arguments in March.

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

The US southern neighbor tightly controls firearms sales, making them practically impossible to obtain legally. Even so, drug-related violence has seen more than 480,000 people killed in Mexico since the government deployed the army to combat trafficking in 2006, according to official figures.

Catherine Stetson, representing the Mexican government before the Supreme Court, said 600,000 US guns are illegally trafficked into Mexico every year, and some companies are even "designing certain guns to target the Mexican market," giving them Spanish names such as "El Jefe."

The case comes against a backdrop of US-Mexico trade tensions with Trump imposing tariffs on imports from Mexico, citing a lack of progress in stemming the flow of drugs such as fentanyl into the US.