Dist.Ct. abused its discretion in granting defendant's motion to dismiss plaintiff's amended complaint based on newly filed affirmative defense of res judicata, where defendants filed instant motion to assert said affirmative defense almost seven years after lawsuit had been filed. Dist. Ct. held erroneous belief that it was required under Massey, 196 F.3d 727, to allow defendants to assert instant res judicata claim as new affirmative defense where, as here, plaintiff filed amended complaint, and Dist. Ct. must exercise sound discretion under Rules 8 and 15 in deciding whether to allow late addition of new affirmative defense. Here, Dist. Ct. abused its discretion, where, although plaintiff was granted leave to file late motion to amend his complaint, plaintiff's amendments to complaint concerned only minor aspects of case that did not change theory or scope of case, and where said amendments had nothing to do with res judicata defense. Fact that Dist. Ct. had instructed defendants to "answer or otherwise plead" after it had granted motion to amend complaint did not require different result. Moreover, on remand, defendants will not be able to assert res judicata defense, since said defense was untimely, where defendants had waited six years to assert said defense, under circumstances where defendants had conducted discovery and asserted said defense prior to pending deadline for filing any summary judgment motion.
