...and is a successor to the old Federal Equity Rule 38, which provided simply: ' when the question is one of common or general interest to many persons...make it impracticable to bring them all before the court, one or more may sue or defend for the whole." Equity jurisdiction exists to provide the courts...

...number of individuals who are named parties to the suit. But there had been one exception. Where persons so numerous as to make it impracticable to bring them all before the court had a common interest (for example a joint interest in some property), which could be adequately...