Here's one I haven't seen before. In Sprint Communications Company L.P. v. WideOpenWest, Inc., C.A. No. 18-361-RGA (D. Del.), the defendant apparently sought to admit company "folklore" in support of its implied license defense.
The Court found that this "folklore" was relevant to the implied license defense:
While arguing for its second motion in limine (D.I. 433), Plaintiff Sprint raised the issue of certain privileged communications. . . . Plaintiffs second motion in limine sought to exclude testimony about company "folklore" regarding a right to practice Sprint's patents. Defendants plan to assert the affirmative defense of implied license, supported by this "folklore" testimony from ...
