Rationale: The young doctrine applies to cases that call for interpretation of Fed law. Where a case questions the state laws it must bring its suit in a state forum.

-    Young invoked when: no state forum available to vindicate fed. interest & to interpret fed. law.
-    Usually, prospective relief is sufficient to invoke Young principle, but this is unusual b/c a quiet title action implicates a special sovereign interest. We must examine its effect on the state first.
-    The state’s interest in its land & waters would be affected as intrusively as a retroactive levy on treasury funds b/c it  would bar the state’s officer form exercising their gov. power over waters deemed by the state to be an integral part of their territory.