On Wednesday, President Joe Biden’s Department of Justice sued the State of Missouri over a new law barring local police from enforcing federal gun laws.

Missouri’s Second Amendment Preservation Act, H.B. 85, which was signed into law late last year, declares many federal gun regulations “invalid,” including statutes covering weapons registration and tracking. Local law enforcement are banned from enforcing federal gun laws that lack an equivalent Missouri law, or risk being sued for $50,000 by private citizens who assert their Second Amendment rights have been violated.

Missouri police are also prohibited from giving “material aid and support” to federal agents and prosecutors in enforcing those “invalid” laws on “law-abiding citizens” — defined as those who Missouri law permits to have a gun.