The role of stare decisis in precluding legal issues in future suits with entirely different litigants. In class actions, absent class members can only be bound upon notice and judicial certification of the class. Absent parties will not be bound when there is a conflict of interest such that the named parties are not adequately represent the interests of absent class members, Hansberry v. Lee. Since there's no mandatory intervention, it's up to existing parties to join necessary parties, Martin v. Wilkes. Multidistrict Litigation Act to coordinate complex litigation in order to reduce redundant discovery.
Parties agree to be bound by results of a test case.