California and other blue states are siding with the Mexican government in its lawsuit against U.S. gun makers like Smith & Wesson, in which Mexico argues the companies are responsible for gun violence south of the border.

Mexico's lawsuit claims that gun manufacturers are liable for gun violence, and a filing from California and other states say they agree that the companies are "fully aware that their firearms were being trafficked into the country and that the companies — not a third party — knowingly violated laws applicable to the sale or marketing of firearms."

Mexico's lawsuit was tossed out by a federal judge in Massachusetts last year, but Mexico has appealed its case to the First Circuit.

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California's Democrat Attorney General Bonta and 17 other Democrat-led states filed an amicus brief in that appeal, and argue that court should overturn the district court. The states also say the Protection of Lawful Commerce in Arms Act (PLCAA) does not shield the companies like Smith & Wesson, Ruger, Glock and others from accountability if their product is sold to dealers who are trafficking the firearms into Mexico illegally.

According to California, legally purchasing a firearm in Mexico is nearly impossible, as the country has one gun store and issues fewer than 50 gun permits per year. California noted that, according to a Government Accountability Office report, an estimated 200,000 firearms are trafficked into Mexico from the United States every year.

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"Gun manufacturers and sellers seem to believe PLCAA gives them a free pass to make and distribute weapons they know are being trafficked and used to terrorize communities in Mexico," California Attorney General Bonta said in a press release this week.

"In most industries, companies are well-aware that they can be held accountable when they violate the law — firearms should be no different. We urge the court to reverse the district court decision and allow this case to move forward," he said.

The PLCAA, enacted in 2005 with bipartisan support, prohibits "civil liability actions from being brought or continued against manufacturers, distributors, dealers, or importers of firearms or ammunition for damages, injunctive or other relief resulting from the misuse of their products by others."

The blue state brief argues that the federal court judge dismissed the case in error, and interpreted the PLCAA to "broadly shield gun manufacturers and sellers from liability for the harms inflicted by firearms and ammunition."

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"While PLCAA does provide a defense to members of the gun industry against certain forms of civil liability, it does not extinguish all forms of accountability for gun manufacturers and sellers," the states wrote in the brief.

The states argued they have a say in the case as "independent sovereigns," as they "bear weighty responsibility for protecting our residents from the risks of gun violence and promoting safety in the use of firearms within our borders."

"Exercising our police powers in service of these goals, we have adopted a range of measures regulating the possession and carrying of firearms," they wrote. "We have also adopted measures to encourage responsible gun manufacturing and sales practices. And when, despite those regulatory efforts, our residents are injured or killed as a result of gun violence, our states have historically provided civil remedies to redress injuries in court."

The states said the PLCAA should allow for civil actions against firearm industry actors if they "knowingly violated a statute applicable to the sale or marketing of a firearm or other qualified product."

Other states included in the brief are Massachusetts, Connecticut, Delaware, Hawai‘i, Illinois, Maryland, Michigan, Minnesota, New Jersey, New Mexico, New York, Oregon, Pennsylvania, Rhode Island and Vermont.

Attorneys for the gun manufacturers did not immediately respond to Fox News Digital's request for comment.