When state officers are charged with violating federal law, they cannot set up the state's federal constitutional sovereign immunity to defeat suits for prospective relief. Decided March 23, 1908 (argued 1907). Opinion of the Court: Rufus W. Peckham → go there Dissenting: Harlan. Applied: the Eleventh Amendment → go there Topic: Federalism. Ex parte Young, 209 U.S. 123 (1908), is a United States Supreme Court case that allows suits in federal courts for injunctions against officials acting on behalf of states of the union to proceed despite the State's sovereign immunity, when the State acted contrary to any federal law or contrary to the Constitution. Although such suits were challenged as actions against the state barred by the Eleventh Amendment, in the early twentieth century, federal courts recognized that they could enjoin state officials from enforcing unconstitutional laws that threatened property rights. Ex parte Young became the leading authority for this principle. Wiki link