What is the test for res judicata?

The policy behind the principle of res judicata is rooted in the need to put an end to litigation. Thus, one who "voluntarily appears, presents his case and is fully heard" should "be thereafter concluded by the judgment of the tribunal to which he has submitted his cause." Baldwin v. Iowa State Traveling Men's Ass'n, 1931, 283 U.S. 522, 526, 51 S.Ct. 517, 518, 75 L.Ed. 1244. The technical rules controlling the application of the doctrine of res judicata may indeed prevent it from applying here since the Alabama order was merely interlocutory, but the principles supporting the rule are surely applicable to the decision made in this case by the district court in Alabama. National chose to present to the Alabama court its contention that the entire action be concluded in the Eastern District of New York. It then had the opportunity to urge that court to stay its own proceeding because of the priority-of-action rule and other considerations. There is no basis in the record for presuming that the court in Alabama did not weigh all these elements in passing on the motions, which called for an exercise of the court's discretion. Nor is there any showing made in this court or below that such discretion was abused, even assuming arguendo that it would be proper for this court to consider such a claim. What the majority affirms, therefore, is a procedure which grants the plaintiff two federal forums in which to present the very same contentions addressed to the court's discretion. If he prevails in either of the two, he is given the relief he desires.