In Aetna Life Insurance Co. v. Haworth, 300 U.S. 227, 57 S.Ct. 461, 81 L.Ed. 617 (1937), the insurer brought a declaratory-judgment action to determine the validity of disability-insurance policies for which the insured had ceased to pay premiums. See id. at 237-38, 57 S.Ct. 461. The insured had claimed that he had been excused from paying premiums, and was entitled to benefits, because he was suffering from a disability that had begun before the unpaid premiums were due. See id. at 238, 57 S.Ct. 461. The insured, however, had not brought suit against the insurer. See id. at 239, 57 S.Ct. 461. The insurer then filed suit because of its concern about having to maintain reserves exceeding $20,000 to cover the potential liability and about the possible loss of evidence over time. See id. Although the Declaratory Judgment Act at the time permitted actions "`in cases of actual controversy,'" id. at 236 n. 1, 57 S.Ct. 461 (quoting 1934 version of the Act), the district court ruled that Aetna's complaint "did not set forth a controversy in the constitutional sense and hence did not come within the legitimate scope of the statute," id. at 236, 57 S.Ct. 461. Aetna petitioned for a writ of certiorari, and the Supreme Court reversed. The Court agreed with the district court that the Declaratory Judgment Act's use of the phrase "`cases of actual controversy' manifestly has regard to the constitutional provision and is operative only in respect to controversies which are such in the constitutional sense." Id. at 239-40, 57 S.Ct. 461. But it disagreed with the lower court's view that Aetna had not presented a controversy. The Court's discussion invoked concepts now commonplace in standing analysis, stating for example that a "controversy" must not be "hypothetical or abstract," but "must be definite and concrete, touching the legal relations of parties having adverse legal interests." Id. at 240-41, 57 S.Ct. 461. And "it must be a real and substantial controversy admitting of specific relief through a decree of conclusive character." Id. at 241, 57 S.Ct. 461.