Under what rule do courts assess whether to dismiss cases due to the absence of an indispensable party?

The correct answer is centered around Federal Rule of Civil Procedure 19, which specifically addresses the issue of indispensable parties. This rule outlines the criteria for determining whether a party is necessary for the resolution of a case and whether their absence would hinder the court's ability to afford complete relief or would impair the absent party's ability to protect their interests.

Rule 19 provides a two-step analysis: first, it identifies parties whose presence in the lawsuit is necessary, and then it evaluates the consequences of proceeding without them. If a court finds that an indispensable party cannot be joined (perhaps due to jurisdictional issues), it must consider whether it is appropriate to dismiss the case altogether or whether there are alternative measures available.

Other rules mentioned in the choices focus on different aspects of civil procedure. For instance, Rule 18 pertains to the joinder of claims, Rule 21 deals with misjoinder and nonjoinder of parties while allowing the court to drop parties, and Rule 22 addresses interpleader actions. However, none of these rules tackle the specific question of assessing indispensable parties as well as Rule 19 does. Thus, it is the rule that primarily dictates the treatment of absent indispensable parties in legal proceedings.