Authorities Cited: United States Patent and Trademark Office U.S. Patent No. 6,148,850 Supreme Court 517 U.S. 370 Circuit Courts 831 F.2d 1017, 1023 52 F.3d 967 90 F.3d 1576, 1583 138 F.3d 1448, 1456 242 F.3d 1337, 1344 327 F.3d 1364, 1369 366 F.3d 1311, 1320 381 F.3d 1111, 1115 415 F.3d 1303 415 F.3d 1335, 1345-1346 445 F.3d 1348, 1353-1355 474 F.3d 1323, 1333 503 F.3d 1295, 1305