The purpose of Fed. R. Civ. P. 13(a) is to prevent multiplicity of actions and to achieve resolution in a single lawsuit of all disputes arising out of common matters.
Defendants were led into an allegedly painless get-rich enterprise. Defendants authorized the purchase of a yacht that would be chartered; the charter fees would allegedly meet all expenses. The purchase was to be financed by defendants' note to plaintiff. Nothing on the note, however, indicated that it was without recourse. The yacht was sold after a default judgment on the note was entered in partial satisfaction of the judgment. Plaintiff brought suit on the judgment was to recover the balance, and to obtain a declaration that the conveyance of defendants' residence to their daughter was fraudulent and void. The court affirmed the ruling for plaintiff.
Did the district court err in its determination that its ruling encompassed all of their claims?
More to the point, there is a purpose in the rule quite apart from concern for the courts -- the interest of the plaintiff in obtaining a complete and final resolution of the essential matters of the litigation. If we accepted defendants' position, a default judgment would be of uncertain value, and represent simply one step toward resolving the dispute between the parties. Instead of having a truly final judgment, the judgment creditor would remain faced with a prospect of litigating other aspects of the same transaction or occurrence at some later time, and in a forum of the defendant's choosing.