The preceding chapters on the federal joinder rules describe a highly flexible system that liberally allows parties to expand the litigation by joining claims in a single action. However, permission under the joinder rules to assert a claim, while necessary, is not sufficient to allow the court to hear it: From early on, we have seen that the court must always have subject matter jurisdiction over a claim if it is to proceed. As you have already read—and you will hear it repeated ad nauseum for the rest of your professional life—the subject matter jurisdiction of the federal courts is limited to the categories of cases enumerated in Article III, §2, of the Constitution.
These two principles, broad joinder under the Rules of Civil Procedure and the need for subject matter jurisdiction over every claim, are on something of a collision course. Frequently, the rules will authorize joinder of claims over which there is no independent basis of subject matter jurisdiction. Such cases pose a dilemma for the courts: The efficiency goals of the Rules favor inclusion of related claims, but the ineluctable need for subject matter jurisdiction appears to bar the court from hearing them.
The problem can arise in a number of contexts. The simplest is the case in which the plaintiff asserts two claims against a nondiverse defendant, one arising under federal law and one under state law. Assume, for example, that Byron brings suit in federal court against Rossetti (a fellow resident of Wisconsin) for violation of a federal age discrimination statute and also claims that the dismissal constitutes a breach of contract. Visually, the case is illustrated as follows:
These claims are properly joined under Rule 18(a). Also, the court clearly has jurisdiction over the federal law claim. But nothing in Article III authorizes jurisdiction over the breach of contract claim: The parties are not diverse, and the claim does not arise under federal law. If Byron sued solely on the contract claim, the federal court would have to dismiss it. Yet the efficiency and consistency goals of the Rules favor hearing Byron’s two claims together, since they involve the same occurrence—the dismissal. Doubtless, the witnesses will be the same on both claims, and much of the same evidence will be relevant to both claims. If the federal court is to litigate this case, it would surely be desirable for it to hear the whole case, including the federal claim and the related state law claim.