In June, Missouri Governor Mike Parson signed the Second Amendment Preservation Act at a gun store in the Kansas City suburb of Lee’s Summit. The law, which takes full effect on August 28, essentially prohibits police in the state from enforcing federal gun restrictions. Agencies whose officers violate the statute can be fined $50,000. 

“The purpose of this is to stand up to the federal government,” Parson told supporters at the signing ceremony. His backdrop was a wall of rifles. “Trust me,” he said, “the states are the firewall to the federal government. If we haven’t learned that in the last 14 months, I don’t know when we’re ever gonna.”

The law puts Missouri at the forefront of a Republican movement against federal gun restrictions that was reinvigorated by the election of President Joe Biden. More than 1,000 local governments and at least 17 states have passed some version of a so-called Second Amendment sanctuary law. Eleven of those states enacted their statutes in 2021. In February, a GOP Congressperson from Georgia, Representative Marjorie Taylor Greene, introduced legislation to halt enforcement of federal gun rules nationwide. 

Many sanctuary laws are preemptive and largely symbolic, but Missouri’s packs a significant legal punch — and its effects are already rippling through the state. City and county officials have said that the law may stop police from testifying against gun offenders in federal court, tapping federal resources to solve local shootings, or working with federal agents to disrupt firearms trafficking. The Missouri Highway Patrol said it plans to quit participating in federal task forces focused on weapons violations. In the city of O’Fallon, the prospect of a fine for seizing weapons during arrests or to protect a resident from suicide so appalled the police chief that he chose to resign rather than grapple with a “flood of weaponized litigation.” 

“The Republican supermajority never really took the time to vet the legislation and think through its impact because they simply wanted to say that they passed something affirming gun rights,” state Senator Lauren Arthur, a Democrat who voted against the sanctuary law, told The Trace. The same Republicans who claim to “back the blue just passed a law that makes it harder for police to do their jobs,” she added.

Victim advocates and law enforcement officials say another notable consequence is the statute’s effect on the police’s ability to remove guns from domestic abusers. In 1996, Congress approved the Lautenberg Amendment, outlawing gun possession for people convicted of misdemeanor domestic violence or subject to a restraining order for stalking or threatening an intimate partner. Many states have passed stronger domestic abuser gun bans, but Missouri is one of the 18 that has no such prohibition on the books. 

As a result, Missouri police typically refer domestic abusers found with guns to federal authorities, leaving it to them to pursue removal. The Second Amendment Preservation Act removes that option, restricting officers from seizing firearms during domestic violence incidents, victim advocates and law enforcement officials say.

The change could endanger domestic abuse survivors in a state where intimate partner homicides are already high, says Matthew Huffman, the public affairs director for the Missouri Coalition Against Domestic and Sexual Violence. Missouri endured the second-highest rate of women killed by men in intimate partner homicides in 2018, according to the Violence Policy Center, an anti-gun-violence advocacy group. Huffman says state judges can order abusers not to possess guns as part of their sentence or restraining order, but the practice is inconsistent.

“It’s not that local law enforcement doesn’t want to help domestic violence survivors who are at risk of an intimate partner homicide,” Huffman said. “The law is putting local law enforcement in a position where they don’t really have the authority to help enforce federal laws that we know keep vulnerable Missourians safe.”

In July, St. Louis, St. Louis County, and Jackson County sued to overturn the sanctuary statute  as a violation of the U.S. Constitution’s Supremacy Clause, which holds that federal law trumps state law. The plaintiffs argue the new measure will preclude St. Louis from enforcing a two-year-old ordinance requiring gun dealers to report customers who fail background checks to police within 24 hours. They also say it will prevent their use of the federal ballistics database, known as NIBIN, which helps investigators link guns to shootings.

The U.S. Justice Department filed a “statement of interest” in support of the lawsuit on August 18, according to The New York Times. In the filing, federal officials say the sanctuary law “undermines law enforcement activities in Missouri, including valuable partnerships federal agencies have developed with state and local jurisdictions.” They note that 12 of the 53 state and local officers who work directly with the Bureau of Alcohol, Tobacco, Firearms and Explosives have withdrawn from joint collaborations, and that state and local agencies have begun to limit federal access to crime-related data, police reports, and investigative records. 

The plaintiffs have asked the judge to issue an injunction to stop the law from taking effect until the case is decided. A hearing on the matter was scheduled for August 19

Court challenges to sanctuary laws in other states have so far been limited. In 2013, the 9th U.S. Circuit Court of Appeals struck down a 2009 Montana law that voided federal oversight of arms made and maintained within state borders. A similar statute in Kansas failed to protect two men from being convicted of federal charges for buying and selling silencers. 

Missouri’s sanctuary law came close to passing in 2013, when Republicans nearly overrode then-Governor Jay Nixon after the Democrat vetoed a version of the bill. The legislation regained momentum after Biden won the White House. Within months of taking office, the president moved to crack down on firearm accessories and homemade, untraceable “ghost guns.” More recently, he announced that his administration would be taking a harder line against gun dealers caught willfully transferring firearms to convicted felons and not conducting background checks. 

The Second Amendment Preservation Act declares as void “all federal acts, laws, executive orders, administrative orders, rules, and regulations” that infringe on people’s Second Amendment rights. Esther Sanchez-Gomez, a litigation attorney with the Giffords Law Center, a gun reform organization, said such vague language is bound to cause police to tread cautiously. “Anything that they think might touch on firearms, even if the law doesn’t necessarily explicitly say they can’t do that, it’s going to create a chilling effect,” she said. “I think that if they were trying to make a sincere attempt to change the law, they would be clearer about what is and isn’t prohibited.”

Kevin Merritt, the executive director of the Missouri Sheriffs’ Association, said the sanctuary law might also dissuade officers from notifying federal authorities about gun stores that break federal law by not running background checks. The ATF licenses gun stores and is responsible for enforcing the background check rule.

As The Trace has previously reported, gun shops often go years or even decades without receiving an ATF inspection. Tips from local law enforcement can cause the ATF to prioritize inspecting a particular gun store, but under the sanctuary law, sharing information with the bureau could put Missouri officers in legal jeopardy, Merritt said. 

The Justice Department in June warned the governor and Missouri Attorney General Eric Schmitt that the sanctuary law was unconstitutional and threatened to disrupt the working relationship between federal and local authorities. Parson and Schmitt, a Republican who is currently campaigning for a U.S. Senate seat, responded by recommitting themselves to enforcing what they called “the most expansive protection for the right to keep and bear arms anywhere in the United States.” Among other things, they cited the 10th Amendment, which gives states the right to deny the use of their resources to enforce federal laws.

A day before the law was signed, Schmitt started pulling prosecutors off federal drug, gun, and carjacking cases in St. Louis and Springfield. He had loaned the personnel as part of the Safer Streets initiative, a joint anti-violence effort that he’d championed. “Local and federal law enforcement have taken great strides, and I believe by working together we can create safer streets,” Schmitt said in announcing the partnership in 2019. In September 2020, Schmitt said the task force was needed in St. Louis because federal penalties for gun offenses were “a lot stiffer.” He touted the initiative again a few months before the sanctuary law passed in May, pointing to the 356 guns recovered and the charges leveled against 289 defendants as evidence of the program’s success. 

Chris Nuelle, a spokesperson for Schmitt, declined to answer questions from The Trace except to deny that the attorney general had pulled prosecutors as a result of the sanctuary law. “We are not pulling back from the Safer Streets Initiative,” he said, adding that a new class of prosecutors would be installed after they cleared background checks. 

Parson’s office provided a statement: ​​“We will reject any attempt by the federal government to circumvent the fundamental right Missourians have to keep and bear arms to protect themselves and their property.”