In a recent development, the Supreme Court has declined to block a federal judge's ruling that deemed a Missouri statute, enacted in 2021, unconstitutional. The law sought to restrict the state and local authorities from cooperating with the federal government in enforcing gun laws. The ruling comes as a blow to state Republican lawmakers who aimed to codify their broad interpretation of the Second Amendment.

The Supreme Court justices, in a brief order, rejected the emergency request filed by the state, upholding the federal judge's decision that federal gun laws take precedence over state laws. Under the Constitution's supremacy clause, federal law generally supersedes state law.

The Missouri law stated that no one in the state had the authority to enforce or attempt to enforce any federal acts or laws that infringe on the right to keep and bear arms. It also declared that fees, taxes, or levies on firearms that could deter law-abiding citizens from purchasing or owning them violate the Second Amendment. Additionally, the law prohibited restrictions on registration or tracking.

Notably, the law allowed gun owners to sue police officers and other state or local officials who assisted in enforcing the covered federal restrictions. However, Justice Neil Gorsuch, in a short opinion joined by Justice Samuel Alito, indicated that private parties could potentially still sue state officials, as they are not bound by the federal judge's ruling.

The Biden administration had sued when the law was enacted, leading to U.S. District Judge Brian Wimes ruling it unconstitutional in March. Although the law was in effect for six months, the St. Louis-based 8th U.S. Circuit Court of Appeals lifted the hold on Wimes' decision on September 29, prompting Missouri to turn to the Supreme Court.

Representing the Biden administration, Solicitor General Elizabeth Prelogar argued that the law is clearly unconstitutional as the supremacy clause prohibits a state from nullifying or impeding federal law. She highlighted that the law had already disrupted the federal government's enforcement of federal law in Missouri and affected their ability to apprehend dangerous criminals.

Missouri Attorney General Andrew Bailey, a Republican, argued that states have the right to choose whether or not to allocate resources to assist the federal government. He further contended that the federal government has not demonstrated any harm caused by Missouri's refusal to cooperate.

The Supreme Court, which currently holds a 6-3 conservative majority, generally supports gun rights. Last year, the court ruled for the first time that the right to bear arms extends outside the home, significantly expanding gun rights. In November, the court is set to hear a new gun case that will examine the scope of that decision in a case concerning the rights of individuals accused of domestic violence to own firearms.