Whether, under the doctrine of Ex parte Young, 209 U.S. 123 (1908), an interstate compact agency may sue a state official to prevent that official from implementing a state law that would be preempted under a congressionally approved interstate compact

QUESTION PRESENTED Interstate compacts are an important and effective means for interstate cooperation, allowing States to resolve disputes or a shared problem while avoiding costly and time-consuming original jurisdiction litigation. Under the Compact Clause of the United States Constitution, Congress has the authority to approve those compacts, and congressional approval gives compacts the status of federal law. Often, congressionally approved interstate compacts create agencies responsible for enforcing the terms of the compact, including through litigation. In a ruling that conflicts with decisions of other courts of appeals, the Third Circuit held below that sovereign immunity bars an interstate compact agency from suing a state official to prevent enforcement of a state law that would violate a congressionally enacted compact. The question presented in this case is: Whether, under the doctrine of Ex parte Young, 209 U.S. 123 (1908), an interstate compact agency may sue a state official to prevent that official from implementing a state law that would be preempted under a congressionally approved interstate compact. @