Last year, the United States Court of Appeals for the First Circuit allowed a lawsuit filed by Mexico's government against a group of American gun manufacturers to go forward.

Yet in a unanimous decision that was released on Thursday, the U.S. Supreme Court opted to overturn that ruling.

Lawsuit initiated

According to the Washington Post, Mexico alleged that between 350,000 to 600,000 firearms are trafficked into Mexico from the United States every year and used by drug cartels to engage in violence.

While Mexico's government did not directly accuse the gun manufacturers of directly colluding with cartel members, it did assert that the companies should have placed tighter controls over the sale of their products.

"The flood of Petitioners’ firearms from sources in the United States to cartels in Mexico is no accident," the Mexican government wrote in its brief.

"It results from Petitioners’ knowing and deliberate choice to supply their products to bad actors, to allow reckless and unlawful practices that feed the crime-gun pipeline, and to design and market their products in ways that Petitioners intend will drive up demand among the cartels," the brief added.

Gun makers point to 2005 law

However, the seven named gun makers responded by asserting that "Mexico's suit has no business in an American court."

As part of their argument for Mexico's lawsuit to be tossed out, they pointed to the U.S. Protection of Lawful Commerce in Arms Act (PLCAA).

Passed in 2005, the legislation shields firearm manufacturers from civil liability with an exception for when a company's violation of law was "a proximate cause of the harm for which relief is sought."

In a 9-0 decision, America's highest judicial body concluded that this "proximate cause" standard had not been met.

Contentions rejected

"The kinds of allegations Mexico makes cannot satisfy the demands of the statute’s predicate exception," Fox News quoted Justice Elena Kagan as writing in the court's majority opinion.

Supreme Court sides with US gunmakers in case centered on Mexican cartel violence https://t.co/0xHz2YXnor

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Kagan highlighted the court's belief that the Mexican government did not "plausibly allege" that the defendants had been "aiding and abetting" drug cartels.

"So this suit remains subject to PLCAA’s general bar: An action cannot be brought against a manufacturer if, like Mexico’s, it is founded on a third party’s criminal use of the company’s product," she concluded.