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:
PARKER v. ELLIS, GENERAL MANAGER, TEXAS PRISON SYSTEM.
No. 38.
Argued January 20, 1960.
Decided May 16, 1960.
Frank M. Wozencraft argued the cause for petitioner. With him on the brief was William F. Walsh.
Leon F. Pesek, Assistant Attorney General of Texas, argued the cause for respondent. With him on the brief were Will Wilson, Attorney General, and Linward Shivers, Assistant Attorney General.
Per Curiam.
This is an application for a writ of habeas corpus brought in the United States District Court for the Southern District of Texas alleging unlawful detention under a sentence of imprisonment following a trial in the state court in which petitioner was, according to his claim, denied due process of law as guaranteed by the Due Process Clause of the Fourteenth Amendment of the United States Constitution. After hearing, the District Court dismissed the petition. The Court of Appeals for the Fifth Circuit, with one judge dissenting, affirmed the order of dismissal, 258 F. 2d 937, to which opinion reference is made for the facts. A petition for certiorari to review this judgment presented so impressive a showing for the exercise of this Court’s discretionary jurisdiction that the case was brought here with leave to the petitioner to proceed in forma pauperis, 359 U. S. 924, and his motion for the assignment of counsel was'duly granted. 359 U. S. 951.
Before the case could come to be heard here, the petitioner was released from the state prison after having served his sentence with time off for good behavior. The case has thus become moot, and the Court is without jurisdiction to deal with the merits of petitioner’s claim. “The purpose of the proceeding defined by the statute [authorizing the writ of habeas corpus to be issued] was to inquire into the legality of the detention, and the only judicial relief authorized was the discharge of the prisoner or his admission to bail.” McNally v. Hill, 293 U. S. 131, 136. “Without restraint of liberty, the writ will not issue.” Id., 138. See also Johnson v. Hoy, 227 U. S. 245. “It is well settled that this court will not proceed to adjudication where there is no subject-matter on which the judgment of the court can operate.” Ex parte Baez, 177 U. S. 378, 390. We have applied these principles to deny the writ of certiorari for mootness on the express ground that petitioner was no longer in respondent’s custody in at least three cases not relevantly different from the present one. Weber v. Squier, 315 U. S. 810; Tornello v. Hudspeth, 318 U. S. 792; Zimmerman v. Walker, 319 U. S. 744. In all these cases there was custody as the basis for habeas corpus jurisdiction until the cases reached here. In Weber, the respondent’s custody ceased because the petitioner had received the benefits of the United States Parole Act. In Tornello the petitioner had been pardoned, and was no longer in the custody of anyone. In Zimmerman petitioner had been unconditionally released and was also no longer in the custody of anyone. These cases demonstrate that it is a condition upon this Court’s jurisdiction to adjudicate an application for habeas corpus that the petitioner be in custody when that jurisdiction can become effective. It is precisely because a denial of a petition for certiorari without more has no significance as a ruling that an explicit statement of the reason for a denial means what it says. Accordingly, the writ of certiorari is dismissed for want of jurisdiction.
Since the case has become moot before the error complained of in the judgment below could be adjudicated, the case is remanded to the Court of Appeals to vacate its judgment and to direct the District Court to vacate its order and dismiss the application.
It is likewise true that “a motion for relief under 28 U. S. C. § 2255 [relevant only to federal sentences] is available only to attack a sentence under which a prisoner is in custody.” 358 U. S., at 420. Contrary to the unconsidered assumption in Pollard v. United States, 352 U. S. 354, this was decided after full deliberation only a year ago. See the opinion of Mr. Justice Douglas, 358 U. S., at 418, and the opinion of Mr. Justice Stewart for the Court on this point, 358 U. S., at 420, in Heflin v. United States, 358 U. S. 415. Of course Rule 35 of the Federal Rules of Criminal Procedure is not available for state sentences.

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: 2