erly reviewable by this Court pursuant to 28 U. S. C. § 1254 (1). Clearly the effect of the order is immediate and irreparable, and any review by this Court of the propriety of the order must be immediate to be meaningful.
Second. We agree with the Court of Appeals that the existence of an actual shortage of gas supplies forms the factual predicate necessary to the Commission's assertion of authority under its transportation jurisdiction, § 1 (b) of the Act, 15 U. S. C. § 717 (b), to approve the curtailment of gas already contracted for. FPC v. Louisiana Power & Light Co., 406 U. S. 621 (1972). Certainly that court could properly conclude that the Commission would have abused its discretion had it approved curtailment plans in the absence of evidence whereby it “could have reasonably believed” the shortage to exist, Citizens to Preserve Overton Park v. Volpe, 401 U. S. 402, 416 (1971), and that “substantial evidence” in the record is necessary to support any such finding by the Commission.
Third. We are of the view, however, that the Court of Appeals overstepped the bounds of its reviewing authority in issuing the order presently before us. First, we have consistently expressed the view that ordinarily review of administrative decisions is to be confined to “consideration of the decision of the agency . . . and of the evidence on which it was based.” United States v. Carlo Bianchi & Co., 373 U. S. 709, 714-715 (1963). “[T]he focal point for judicial review should be the administrative record already in existence, not some new record made initially in the reviewing court.” Camp v. Pitts, 411 U. S. 138, 142 (1973). If the decision of the agency “is not sustainable on the administrative record made, then the . . . decision must be vacated and the matter remanded ... for further consideration.” Id., at 143. Clearly it is this mode of review that is contem