Reexamination for Expired Digital Technology Patent

Scott Daniels | October 1, 2009

The PTO granted ex parte reexamination of U.S. Patent No. 5,051,799 belonging to Digital Technology Licensing, and entitled “Digital Output Transducer.” The request was filed by Kyocera Wireless.

Although the ‘799 patent expired on February 17, 2009, a request for reexamination may be filed at any time during the patent’s “period of enforceability.” That period is determined by adding six years to the date on which the patent expires, so that in this case the period of enforceability extends to February 17, 2015. One qualification, however, is that there is no possibility of amending claims of an expired patent.

Kyocera asserted in its request that claims 18 and 20 of the ‘799 patent are unpatentable as being anticipated by each of six prior art references and obvious over two additional references. The PTO found that an SNQ existed with respect to each of the eight references.

An interesting feature of the request was its assertion that the ‘799 patentee had admitted in earlier litigation that a “whereby clause” in claim 18 was not a limitation and thus could not be a basis for distinguishing the claim over the prior art. The PTO agreed, finding that the “whereby clause” was “irrelevant with regard to the question of whether an SNQ is raised.”

Also interesting is the PTO’s analysis of the original patent prosecution in its determination that SNQs exist: since the reason for the original allowance of the claims was unclear, “any reference including a substantial number of teachings of limitations drawn from claim 18 will be accepted as raising an SNQ for that claim.”

Further, the PTO stated that the cited art raised an SNQ regarding claim 20 because it depends on claim 18.

The ‘799 patent is currently the subject of a suit in the Southern District of New York where Kyocera seeks a declaratory judgment that the patent is invalid and unenforceable, and not infringed. Digital Technology replied with a third-party complaint accusing a host of wireless makers of infringing the ‘799 patent.

Kyocera moved on August 5, 2009 to stay the case pending resolution of the reexamination. The motion is now being briefed.

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