William O. Douglas,
England v. Louisiana State Board of Medical Examiners…
“ Yet we now hold that if a party, who is sent by the federal court to the state courts for a preliminary ruling, submits the whole problem to those courts-that is, the constitutional as well as the bare bones of the state law question-he is presumed to have elected to try his case there rather than in the federal courts, unless he expressly reserved the right to return to the federal tribunal. Perhaps the Court does that to avoid the consequences of res judicata. But res judicata is not a constitutional principle; it has no higher dignity than the principle we announce today. ”
