Necessary Party Law and Legal Definition

A necessary party is a person or entity whose interests are at stake in the outcome of a lawsuit, whose absence as a party in the suit prevents a judgment on all issues, but who cannot be joined in the lawsuit because that would deny jurisdiction to the particular court. A necessary party who is not in the suit differs from an "indispensable party," who must be joined if the lawsuit is to proceed, and from a "proper party," who could be joined but is not essential.

There are generally three ways that someone can be a necessary party:

  1. in the absence of the party complete relief cannot be provided to existing parties


    the absent party claims an interest relating to the subject of the action and a disposition of the action without that person may
  2. as a practical matter impair his ability to protect that interest OR
  3. leave the persons already parties subject to a substantial risk of incurring double, multiple or otherwise inconsistent obligations.