In this 5-4 decision, the U.S. Supreme Court declared in 1997 certain key provisions of the Brady Handgun Violence Prevention Act unconstitutional. While the Brady Act was an attempt at federal gun control, this is not a Second Amendment case. It is a Tenth Amendment case. Justice Scalia, writing for the majority, held that Congress is constitutionally prohibited from infringing on the sovereignty of states by commanding local law enforcement agents to participate in a federal regulatory scheme, subject to federal sanction if they do not.
The case itself: Printz v. United States (1997)
Follow The Law with D.K. Williams on Twitter @TheLawDKW