opinion: DIXON v. DUFFY, WARDEN.
  No. 4.
  Argued October 16, 1951.
  Continued November 5, 1951.
  Further continued May 12, 1952.
  Decided December 8, 1952.
  Franklin C. Stark, acting under appointment by the Court, argued the cause and filed a brief for petitioner.
  Clarence A. Linn, Assistant Attorney General of California, argued the cause for respondent. With him on the brief were Edmund G. Brown, Attorney General, and Howard S. Goldin, Deputy Attorney General.
  Mr. Chief Justice Vinson
  delivered the opinion of the Court.
  This case originated on October 21, 1950, when petitioner, a prisoner in San Quentin, filed an application for a writ of habeas corpus in the Supreme Court of California. That court, summarily, but with two dissents, denied the application. To review this decision, petitioner applied to this Court for certiorari. The Court granted the petition, 341 U. S. 938, and thereafter appointed counsel to represent the petitioner. 342 U. S. 805.
  The Attorney General of California appeared for respondent. At the bar of this Court, he argued that the judgment of the Supreme Court of California rested on an adequate nonfederal ground. Admitting that habeas corpus is ordinarily an available means to California prisoners to challenge the constitutionality of the proceedings which resulted in their incarceration, the Attorney General told us that the writ was unavailable in this particular case, to this particular petitioner because he could have and should have presented his federal claim in an appeal from his original conviction. Counsel for petitioner vigorously opposed this contention, insisting that habeas corpus was an available remedy under California law, that the federal question was properly before the court.
  This Court, of course, does not sit to determine matters of state law; nor is it the appropriate forum to resolve the argument raised by the earnest objections of the Attorney General of California.
  Accordingly, we followed our precedents. We continued the cause “for such period” as would “enable counsel for petitioner to secure a determination from the Supreme Court of California as to whether the judgment herein was intended to rest on an adequate independent state ground or whether decision of the federal claim was necessary to the judgment rendered.” 342 U. S. 33, 34. (Emphasis supplied.)
  Counsel for petitioner, in December 1951, duly filed in the Supreme Court of California a “Petition for Determination of Basis of Judgment” which requested an expression by that court on the issue raised by our order. Subsequently, the Clerk of this Court received a letter from the Clerk of the Supreme Court of California relative to this question. But we received no official determination of the issue from the Supreme Court of California.
  We could not regard the letter from the Clerk of the Supreme Court of California as a “sufficient ‘determination’ of the question raised in our order of November 5, 1951.” Therefore, on May 12, 1952, we “further continued” the cause on our docket to enable counsel for petitioner to secure from the Supreme Court of California its official determination as requested by our earlier order. 343 U. S. 393.
  Though some months have now elapsed, we still have received no advice from the Supreme Court of California. We are informed, however, that the California court advised petitioner’s counsel informally that it doubted its jurisdiction to render such a determination. And, although counsel subsequently submitted briefs to the contrary, the California court again informed counsel, through its Clerk, that it was powerless, for want of jurisdiction, to issue any further official expression on the case. It appears, then, that so long as this cause continues on our docket, counsel cannot procure that which we asked him to procure.
  We granted certiorari in this case “because of a serious claim that petitioner had been deprived of his rights under the Federal Constitution.” 342 U. S. 33. This Court, alone, is the final arbiter of such a claim, and our grant of certiorari should entitle petitioner to the chance to have the matter resolved by this Court — provided that the state judgment was not based on an adequate state ground. If the state judgment was based on an adequate state ground, the Court, of course, would be without jurisdiction to pass upon the federal question. Doubt has since arisen that such, jurisdiction exists. These circumstances should not now act to deprive petitioner of his day in this Court, but they do require that we take scrupulous care, as we have so often done before, to determine our jurisdiction. This involves further delay, and in this case further delay is regrettable. But delay is necessary unless we are to resolve the jurisdictional issue by simply assuming the nonexistence of an adequate state ground though in fact one may exist.
  To the end that the doubt in this case may be resolved, we vacate the judgment of the Supreme Court of California and remand the cause for further proceedings. A new judgment may be entered, and petitioner also may be informed by an official determination from the Supreme Court of California whether or not that judgment rests on an adequate state ground.
  So ordered.
  Loftus v. Illinois, 334 U. S. 804 (1948); Herb v. Pitcairn, 324 U. S. 117 (1945).
  See Neilson v. Lagow, 12 How. 98, 109-110 (1852).
  See, e. g., Jennings v. Illinois, 342 U. S. 104 (1951); Loftus v. Illinois, supra; Herb v. Pitcairn, supra. Minnesota v. National Tea Co., 309 U. S. 551 (1940); Honeyman v. Hanan, 300 U. S. 14 (1937).
  Cf. Jennings v. Illinois, supra; Minnesota v. National Tea Co., supra; Honeyman v. Hanan, supra.
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