To: mishedlo who wrote (58445 ) 10/22/2000 11:12:17 AM From: Bilow Read Replies (2) | Respond to of 93625 Hi mishedlo; I'm not the best reference on patent law. Hitachi claimed "prior art" on the SDRAM/DDR Rambus patents, I'm not sure if that is the same thing as "obvious", but my guess is that what I call "obvious", the lawyers call "prior art":SIXTH AFFIRMATIVE DEFENSE By reason of proceedings in the United States Patent and Trademark Office during the prosecutions of the family of applications leading to the Patents-in-Suit, the claims of those patents were limited by prosecution history estoppel, as well as by the prior art , so that Rambus is now estopped from maintaining that the Patents-in-Suit are of such scope as to cover or embrace any of the accused products or processes. theregister.co.uk -- Carl P.S. "Prosecution history estoppel " has to do with how the patent holder got the patent office to accept the patent (i.e. prosecuted the patent) by adding enough language to distinguish the invention from prior art. If I am wrong about this, I am sure that Zeev will correct me, it is way outside my specialty:A competitor studying the prosecution history of the patent in the PTO should also be able to discern whether the patent applicant disclaimed coverage of certain subject matter in order to obtain the patent. The doctrine of "prosecution history estoppel," as it is now known, (2) limits the application of the doctrine of equivalents by precluding the patent holder from recapturing subject matter surrendered during prosecution. See Exhibit Supply Co. v. Ace Patents Corp., 315 U.S. 126, 136-37, 52 USPQ 275, 279-80 (1942); Cybor Corp. v. FAS Techs., Inc., 138 F.3d 1448, 1460, 46 USPQ2d 1169, 1178 (Fed. Cir. 1998) (en banc). This estoppel typically applies when an applicant amends or cancels claims rejected by an examiner as unpatentable in light of the prior art. See, e.g., Texas Instruments, Inc. v. U.S. Int'l Trade Comm'n, 988 F.2d 1165, 1174, 26 USPQ2d 1018, 1025 (Fed. Cir. 1993). The amendment in effect acts as a disclaimer of certain subject matter in order to obtain allowance of the claims: By the amendment, [the patent holder] recognized and emphasized the difference between the two phrases and proclaimed his abandonment of all that is embraced in that difference. . . . The difference which he thus disclaimed must be regarded as material, and since the amendment operates as a disclaimer of that difference it must be strictly construed against him. aipla.org