How does joinder affect subject matter jurisdiction?

Joinder affects subject matter jurisdiction by allowing additional claims or parties to be brought into a case without creating new jurisdictional requirements on its own. When claims are joined, they do not independently establish subject matter jurisdiction; rather, they expand the case's scope under the existing jurisdiction provided by the original claims. This means that a court can consider additional claims or parties as long as the original claim meets the jurisdictional criteria, such as federal question or diversity jurisdiction.

For instance, if a plaintiff has an original claim that satisfies the diversity jurisdiction requirement, they may join additional claims related to the same transaction or occurrence. The court can then hear all these claims together, which promotes judicial efficiency and consistency in legal proceedings. However, the joined claims must still relate back to the original claim to ensure that they fall under the court's established subject matter jurisdiction.

In contrast, options that suggest joinder creates independent jurisdiction, limits cases to original claims, or nullifies the need for original claims do not accurately reflect how joinder works in the context of subject matter jurisdiction.