concurring.
I offer the following few words in light of Mr. Justice Rehnquist’s concurrence in which he discusses the impact on a pending federal action of a later filed criminal prosecution against the federal plaintiff, whether a federal court may enjoin a state criminal prosecution under a statute the federal court has earlier declared unconstitu*477tional at the suit of the defendant now being prosecuted, and the question whether that declaratory judgment is res judicata in such a later filed state criminal action.
It should be noted, first, that his views on these issues are neither expressly nor impliedly embraced by the Court’s opinion filed today. Second, my own tentative views on these questions are somewhat contrary to my Brother’s.
At this writing at least, I would anticipate that a final declaratory judgment entered by a federal court holding particular conduct of the federal plaintiff to be immune on federal constitutional grounds from prosecution under state law should be accorded res judicata effect in any later prosecution of that very conduct. There would also, I think, be additional circumstances in which the federal judgment should be considered as more than a mere precedent bearing on the issue before the state court.
Neither can I at this stage agree that the federal court, having rendered a declaratory judgment in favor of the plaintiff, could not enjoin a later state prosecution for conduct that the federal court has declared immune. The Declaratory Judgment Act itself provides that a “declaration shall have the force and effect of a final judgment or decree,” 28 U. S. C. § 2201; eminent authority anticipated that declaratory judgments would be res judicata, E. Borchard, Declaratory Judgments 10-11 (2d ed. 1941); and there is every reason for not reducing declaratory judgments to mere advisory opinions. Toucey v. New York Life Insurance Co., 314 U. S. 118 (1941), once expressed the view that 28 U. S. C. § 2283 forbade injunctions against relitigation in state courts of federally decided issues, but the section was then amended to overrule that case, the consequence being that “[i]t is clear that the Toucey rule *478is gone, and that to protect or effectuate its judgment a federal court may enjoin relitigation in the state court.” C. Wright, Federal Courts 180 (2d ed. 1970). I see no more reason here to hold that the federal plaintiff must always rely solely on his plea of res judicata in the state courts. The statute provides for “[fjurther necessary or proper relief . . . against any adverse party whose rights have been determined by such judgment,” 28 U. S. C. § 2202, and it would not seem improper to enjoin local prosecutors who refuse to observe adverse federal judgments.
Finally, I would think that a federal suit challenging a state criminal statute on federal constitutional grounds could be sufficiently far along so that ordinary consideration of economy would warrant refusal to dismiss the federal case solely because a state prosecution has subsequently been filed and the federal question may be litigated there.