Pendent and Ancillary Jurisdiction Distinguished

Pendent and ancillary jurisdiction are the traditional terms for the two ways that a cause of action without its own source of federal SMJ can be part of the same constitutional case or controversy as a cause of action that does have its own source of federal SMJ

Pendent Jurisdiction

Joined cause of action arises out of the common nucleus of operative facts as a cause of action with an independent source of federal SMJ
AND is
Joined by the same party that brought the cause of action that has an independent source of federal SMJ
E.G. Joinder of claims allowed under R. 18(a) and required under claim preclusion.

NOTE: Pendent party jurisdiction is pendent jurisdiction in which the pendent cause of action brings in a new party.

Ancillary Jurisdiction

Joined cause of action arises out of the common nucleus of operative facts as a cause of action with an independent source of federal SMJ
AND is
Brought by someone other than the person that brought the cause of action that has an independent source of federal SMJ E.G.:Compulsory Counterclaims under R. 13(a) or Cross-Claims under R. 13(g)

OR

Joined cause of action, although not really arising out of the common nucleus of operative fact, has legal rights that were activated by the cause of action that has an independent source of federal SMJ
E.G.: Impleader under R. 14(a) or Supplementary proceedings under R. 69