“ Stratton does not stand for the broad proposition that a court of appeals is powerless ever to give any guidance when a single judge has erroneously invaded the province of a three-judge court. The Court of Appeals clearly stated its opinion that a court of three judges ought to have been convened to consider this litigation. That view was correct and should have been followed upon the petitioner's renewed motion that such a statutory court be impaneled. ”

“ When an application for a statutory three-judge court is addressed to a district court, the court's inquiry is appropriately limited to determining whether the constitutional question raised is substantial, whether the complaint at least formally alleges a basis for equitable relief, and whether the case presented otherwise comes within the requirements of the three-judge statute. ”

“ It is so ordered.
Case remanded.
Mr. Justice FRANKFURTER took no part in the decision of these cases.
Mr. Justice HARLAN and Mr. Justice WHITE took no part in the consideration or decision of these cases. ”