Obvious examples are Frank Easterbrook in ProCD, Inc. v. Zeidenberg, 86 F.3d 1447 (7th Cir. 1996), and Hill v. Gateway 2000, Inc., 105 F.3d 1147 (7th Cir. 1997). Alex Kozinski provides further example in his attack on the California parol evidence rule (though he was Erie-bound) in his notorious Trident opinion. See
Trident Center v. Conn. Gen. Life Ins. Co., 847 F.2d 564 (9th Cir. 1988).