What is the test for a declaratory judgment in a personal injury case?

6 Cf. Samuels v. Mackell, 288 F.Supp. 348 (S.D.N.Y.1968) (three-judge court), aff'd, 401 U.S. 66, 91 S.Ct. 764, 27 L.Ed. 2d 688 (1971) (affirmed "solely on the ground that, in the appropriate exercise of the court's discretion, relief by way of declaratory judgment should have been denied without consideration of the merits." 401 U.S. at 73, 91 S.Ct. at 768).