Plenary consideration of this case, and indeed the opinion of the majority o'f this Court, have made it clear that the Court of Appeals dealt with the factual issues, involved on the basis of a concession by the respondent and the jury’s answer to Interrogatory No. 1. ' It is therefore'now apparent that this case presents no. question concerning the classification of these issues as for the court or for the jury under the decision in Byrd v. Blue Ridge Rural Cooperative, Inc., 356 U. S. 525, and that the premise on which we granted certiorari was accordingly a mistaken one. And whether or not the Court of Appeals in acting as it did was correct, in .its assessment of the trial record is certainly not a matter justifying the exercise of .our certiorari power within the criteria of Rule 19. I therefore agree with my Brother Frankfurter that the writ of certiorari should be dismissed as improvidently granted, and join in his dissenting opinion.
Even if a Byrd issue could be considered as properly presented, the most that should be done is to remand the *286case to the Court of Appeals for further consideration in light of that decision. A retrial of this case would be justified under Byrd only if the Pennsylvania practice treating factual issues under § 104 of. the Workmen’s Compensation Act as for the court, instead of for the jury, see Persing v. Citizens Traction Co., 294 Pa. 230, 144 A. 97; Vescio v. Pennsylvania Electric Co., 336 Pa. 502, 9 A. 2d 546, is merely a “form and mode” of procedure rather than “an integral part” of the rights created by the Act. Before deciding such a difficult and subtle question of local law; this Court should, have the aid of the Court of Appeals whose -members are more competent than we to speak ón Pennsylvania law.