What follows is an opinion from the Supreme Court of the United States. Your task is to determine the bases on which the Supreme Court rested its decision with regard to the legal provision that the Court considered in the case. Consider "judicial review (national level)" if the majority determined the constitutionality of some action taken by some unit or official of the federal government, including an interstate compact. Consider "judicial review (state level)" if the majority determined the constitutionality of some action taken by some unit or official of a state or local government. Consider "statutory construction" for cases where the majority interpret a federal statute, treaty, or court rule; if the Court interprets a federal statute governing the powers or jurisdiction of a federal court; if the Court construes a state law as incompatible with a federal law; or if an administrative official interprets a federal statute. Do not consider "statutory construction" where an administrative agency or official acts "pursuant to" a statute, unless the Court interprets the statute to determine if administrative action is proper. Consider "interpretation of administrative regulation or rule, or executive order" if the majority treats federal administrative action in arriving at its decision.Consider "diversity jurisdiction" if the majority said in approximately so many words that under its diversity jurisdiction it is interpreting state law. Consider "federal common law" if the majority indicate that it used a judge-made "doctrine" or "rule; if the Court without more merely specifies the disposition the Court has made of the case and cites one or more of its own previously decided cases unless the citation is qualified by the word "see."; if the case concerns admiralty or maritime law, or some other aspect of the law of nations other than a treaty; if the case concerns the retroactive application of a constitutional provision or a previous decision of the Court; if the case concerns an exclusionary rule, the harmless error rule (though not the statute), the abstention doctrine, comity, res judicata, or collateral estoppel; or if the case concerns a "rule" or "doctrine" that is not specified as related to or connected with a constitutional or statutory provision. Consider "Supreme Court supervision of lower federal or state courts or original jurisdiction" otherwise (i.e., the residual code); for issues pertaining to non-statutorily based Judicial Power topics; for cases arising under the Court's original jurisdiction; in cases in which the Court denied or dismissed the petition for review or where the decision of a lower court is affirmed by a tie vote; or in workers' compensation litigation involving statutory interpretation and, in addition, a discussion of jury determination and/or the sufficiency of the evidence.

Opinion:
BERGER v. CALIFORNIA.
No. 221,
Misc.
Decided January 13, 1969.
Thomas C. Lynch, Attorney General of California, William E. James, Assistant Attorney General, and Marvin A. Bauer, Deputy Attorney General, for respondent.
Per Curiam.
Petitioner was convicted of robbery and kidnaping for the purpose of robbery. The victim, one Carl Arthur Dunston, testified against petitioner at a preliminary hearing; there was evidence that at the time of the trial Dunston was in Colorado. A state investigator tried to contact Dunston on the telephone; he got through to some of Dunston’s relatives and to his employer, but not to Dunston himself. Although two telegrams were received, allegedly from Dunston, no subpoena was served. At trial, the transcript of Dunston’s preliminary hearing testimony was introduced into evidence. On appeal, the Court of Appeal for the Second Appellate District of California held that this procedure did not deny petitioner his Sixth Amendment right to be confronted with the witnesses against him since Dunston was absent from the State of his own free will and since petitioner’s counsel had had an adequate opportunity to cross-examine Dunston at the preliminary hearing. 258 Cal. App. 2d 622, 66 Cal. Rptr. 213 (1968). The California Supreme Court denied petitioner a hearing on April 4, 1968. Nineteen days later we held in the case of Barber v. Page, 390 U. S. 719, that the absence of a witness from the jurisdiction would not justify the use at trial of preliminary hearing testimony unless the State had made a good-faith effort to secure the witness’ presence. The sole question in this case is whether the holding of Barber v. Page should be given retroactive application. We think that it should.
Clearly, petitioner’s inability to cross-examine Dunston at trial may have had a significant effect on the “integrity of the fact-finding process.” Linkletter v. Walker, 381 U. S. 618, 639 (1965); cf. Roberts v. Russell, 392 U. S. 293 (1968); McConnell v. Rhay, ante, p. 2 (1968). As we pointed out in Barber v. Page, one of the important objects of the right of confrontation was to guarantee that the fact finder had an adequate opportunity to assess the credibility of witnesses. 390 U. S., at 721. And California’s claim of a significant countervailing interest based upon its reliance on previous standards, see Stovall v. Denno, 388 U. S. 293, 297 (1967), is most unpersuasive. Barber v. Page was clearly foreshadowed, if not preordained, by this Court’s decision in Pointer v. Texas, 380 U. S. 400 (1965), which was handed down more than a year before petitioner’s trial. Accordingly, we can see no reason why Barber v. Page should not be given fully retroactive application.
The motion for leave to proceed in forma pauperis and the petition for writ of certiorari are granted. The judgment of the Court of Appeal is vacated and the case is remanded for reconsideration in light of this Court’s decision in Barber v. Page, 390 U. S. 719 (1968).
It is so ordered.

Question: What is the basis of the Supreme Court's decision?

Choices:
judicial review (national level)
judicial review (state level)
Supreme Court supervision of lower federal or state courts or original jurisdiction
statutory construction
interpretation of administrative regulation or rule, or executive order
diversity jurisdiction
federal common law

Answer: 6