Is res judicata barred from the present action?

First, defendants contend that res judicata bars plaintiffs' present action because the same issues have been litigated in state court. This court has already rejected this argument. In Tovar v. Billmeyer, 609 F.2d at 1293-94, we held that "[a] free and unreserved submission to the state court of all federal claims for complete and final resolution is necessary to bar return to the federal court." And, as we noted in Tovar, plaintiffs have consistently made an "explicit reservation of constitutional issues." Id. at 1293. Defendants' res judicata argument is thus without merit.