terest of justice, the adverse party is entitled to scp the writing. Fed.R.Evid. 612; see Sporck l. Peil, 759 F.2d 312 317 (3d Cir.1985); But- ler Mfg. Co., Inc. . Americold Corp., 148 D. F.R. 275, 278 .Kan.1993); 4 Jack B. Weinstein and Margaret A. Berger, Wein- stein's federal Evidence § 612.07[1] (2d e