Missouri’s law prohibiting state officials from enforcing federal gun laws believed to run afoul of the Second Amendment suffered a serious blow Friday. The U.S. Supreme Court declined a state request to reinstate the statute.

The high court turned aside a request by Missouri to reverse a federal judge’s ruling against the Second Amendment Preservation Act (SAPA). The 2021 law was targeted by the Biden administration the following year with the claim that it violated the Constitution’s “supremacy clause.”

This established the principle that federal laws supersede state laws.

Justice Clarence Thomas, the driving force behind last year’s key Bruen decision, publicly dissented.

The White House argued that Missouri lawmakers undermined public safety and interfered with federal firearms regulations. The statute ended the cooperation of local and state law enforcement agencies with federal authorities in the enforcement of controversial federal gun laws.

The Missouri law was invalidated in March by U.S. District Judge Brian Wimes. He determined that the act ran afoul of federal authority to enforce “firearms regulations designed by Congress for the purpose of protecting citizens.”

Missouri officials are not going down quietly.

Attorney General Andrew Bailey defiantly responded to the ruling. “Today’s SCOTUS ruling on SAPA was a purely procedural matter. We remain undeterred in our defense of Missourians’ Second Amendment rights,” he wrote on X, the platform formerly known as Twitter.

Bailey added the state would revisit the issue at the Eighth Circuit.

The legal challenge will proceed in lower courts as the law is blocked from being enforced. It could eventually be returned to the high court for a final decision. 

The state passed the act two years ago to counter what lawmakers believed were unconstitutional actions by the federal government. Among laws Missouri officials objected to were mandatory registrations and restrictions on firearms transfers.