may issue does not mean it must issue. See SMA Life Assurance Co. v. Sanchez-Pica, 960 F.2d 274, 276 (1st Cir.1992). The court needs a “substantial justification” for issuing such injunction. Id. at 277. And the general prerequisites for injunctive relief must usually be met. See James, 733 F.2d at 993. Based on concerns of comity and federalism, a federal court must ask whether requiring the moving party to raise a preclusion defense in state court would be the wiser course. At the same time, the court must remain mindful that the state court’s rejection of a preclusion defense effectively proscribes a federal court from issuing a subsequent injunction to effectuate its judgment. See Parsons Steel, Inc. v. First Alabama Bank, 474 U.S. 518, 524, 106 S.Ct. 768, 88 L.Ed.2d 877 (1986) (<HOLDING>). With these precepts in mind, we decline to
holding that res judicata prevents relitigation of a claim that was previously the subject of a valid and final decision of this court holding that because relitigation of issue was barred by collateral estoppel res judicata determination of finality of judgment dismissed for lack of standing was not relevant holding that res judicata precludes relitigation of issue that was or could have been decided in enforcement order that was not appealed holding the relitigation exception was limited to those situations in which the state court has not yet ruled on the merits of the res judicata issue holding that a dismissal on statute of limitations grounds is an adjudication on the merits for purposes of res judicata