Schultz v. iGPS Co. LLC, No. 10 C 71, Slip. Op. (N.D. Ill. Jan. 3, 2011) (Hibbler, Sen. J.)

Judge Hibbler granted in part defendant's Fed. R. Civ. P. 15 motion to amend its affirmative defenses. The doctrine of assignor estoppel did not ban defendant's invalidity and inequitable conduct defenses. An assignor is estopped from challenging the validity and enforceability of its assigned patent, but that estoppel is personal to the assignee. Because plaintiff was not the assignee, he had no right to assert estoppel. Furthermore, to determine whether defendants were in privity with the assignor would require facts beyond the complaint and was, therefore, not resolvable in a motion to dismiss.

The Court, however, did not accept defendants' inequitable conduct defenses because they failed to plead the necessary intent with particularity. Defendants only alleged that patentee failed to pay its maintenance fees and then improperly revived the patents, without more. Defendants were granted leave to replead those defenses, if possible, with sufficient facts.