they might have had merit. See IGEN Intl, Inc. v. Roche Diagnostics GmbH, 335 F.3d 303, 308-09 (4th Cir. 2003); Pleasurecraft Marine Engine Co. v. Thermo Power Corp., 272 F.3d 654, 657 (4th Cir. 2001). And we have applied the doctrine despite its potentially significant impact. See, e.g., Carter v. Lee, 283 F.3d