March 3, 2017

Disavowal is Not Limited to What is Necessary; A Patentee May Give Up More than Necessary

By Bryan K. Wheelock, Principal

In Technology Properties Limited LLC v. Huawei Technologies Co., Ltd., [2016-1306, 2016-1307, 2016-1309, 2016-1310, 2016-1311] (March 3, 2017), the Federal Circuit vacated and remanded the case because the district court erred in a portion of its construction of “entire oscillator” in U.S. Patent No. 5,809,336 on a microprocessor with two independent clocks.

The claims require “an entire oscillator disposed upon said integrated circuit substrate and connected to said central processing unit.”  The district court construed the term to mean “an oscillator located entirely on the same semiconductor substrate as the central processing unit that does not require a control signal and whose frequency is not fixed by any external crystal.”  Appellee argued that the second part of this construction was required because of disclaimers made during prosecution to overcome Magar, U.S. Patent No. 4,503,500, and Sheets, U.S. Patent No. 4,670,837.

The Federal Circuit began noting that an applicant’s statements to the PTO characterizing its invention may give rise to prosecution disclaimer.  The Federal Circuit said that prosecution disclaimer can arise from both claim amendments and arguments made to the PTO, but does not apply unless the disclaimer is “both clear and unmistakable to one of ordinary skill in the art.”

When determining whether disclaimer applies, applicant’s statements must be considered in the context of the entire prosecution.  If the statements are ambiguous or amenable to multiple reasonable interpretations, prosecution disclaimer is not established.

After examining the applicants arguments regarding Magar during prosecution, the Federal Circuit agreed with the district court’s conclusion that the “entire oscillator” must be a variable frequency oscillator rather than a fixed-frequency crystal.  The Federal Circuit said that the disclaimer may not have been necessary, but the statements made to overcome Magar were clear and unmistakable.

The Federal Circuit said that the patent owner presented clear and concise arguments about the distinctions between Magar and the patent in its briefing, and add that had those same arguments been made to the Patent Office, the construction may have been different because the patentee likely disclaimed more than was necessary to overcome the examiner’s rejection.  However, the Federal Circuit admonished:

the scope of surrender is not limited to what is absolutely necessary to avoid a prior art reference; patentees may surrender more than necessary.

As to disclaimers based upon Sheets, the Federal Circuit found that the district court went too far in limiting an “entire oscillator” to one “that does not require a control signal.”  The Federal Circuit said that this was beyond the arguments made by application that the term is properly construed as one “that does not require a command input to change the clock frequency.”

The Federal Circuit indicated that its minor modification to the district court’s construction likely does not affect the outcome in this case, because the parties stipulated to non-infringement under the district court’s construction, the proper course was to vacate.