Duplan (P) sued Chavanoz (D) over patent and antitrust issues. P sought discovery of D's attorney settlement agreements with Leesona Corporation and information relating to D's knowledge of prior art involved with its patents. From the directive of an earlier appeal, the court examined documents and ordered 105 of them produced. D objected in that some of them contained mental impressions, conclusions, opinions, and legal theories of attorneys. The district court ordered production despite this objection in that P demonstrated substantial need and undue hardship and that even though Rule 26(b)(3) accords an absolute privilege during litigation, that immunity ceased after litigation.