Citing prosecution disclaimer from the patentee’s assertions of its “simple” invention to overcome obviousness rejections, the U.S. Court of Appeals for the Federal Circuit affirmed the district court’s claim construction, which included a negative claim limitation that disposed of plaintiff’s case. RFID Tracker, Ltd. v. Wal-Mart Stores, Inc., et al., Case No. 08-1412, (Fed. Cir., Aug. 18, 2009) (Rader, J.; Linn, J.; Dyk, J.; per curiam) (non-precedential).

RFID sued Wal-Mart for infringement of its patent directed to an inventory control system that included radio frequency identification (RFID) tags, an interrogator/reader and a computer. Apparatus claim 1 of the patent recited an “interrogator/reader” that included a “field generator” and a “receiver.” Method claim 15 of the patent recited “generating a field … with an interrogator/reader.” The district court construed the claim term “interrogator/reader” of claims 1 and 15 to mean “a field generator and a receiver, but not a transmitter.” (Emphasis supplied.) Based on this negative claim limitation RFID Tracker stipulated to non-infringement. After the district court entered a final judgment, RFID Tracker appealed.

On appeal RFID Tracker argued that since the claim term in dispute used the open language “includes,” the negative limitation in the district court’s claim construction was inappropriate. Wal-Mart, citing to the prosecution, argued that RFID Tracker has disclaimed a broader construction during prosecution before the U.S. Patent and Trademark Office (USPTO). During prosecution, the applicant differentiated its claims over two § 103(a) references raised by the examiner, arguing that “its claimed interrogator/reader was simple, unlike the complex readers of the prior art that contained and used a transmitter to send commands to the tags,” that “the interrogator/reader is nothing more than a receiver” and that “[t]he [claimed] method … requires no polling and no transmission.” To a similar rejection in a parent application, the applicant argued that, “the present technology only requires that the interrogator generate a field and receive tag signals,” which it argued was a “fundamental” distinction.

The Federal Circuit, citing Computer Docking, noted that “a patentee may limit the meaning of a claim term by making a clear and unmistakable disavowal of scope during prosecution,” and, citing N. Am. Container, further noted that “if the applicant unequivocally disavows claim scope, the doctrine of prosecution disclaimer applies even if the disclaimer results in a negative claim limitation.” As for statements made in the parent application, the Court noted that “prosecution disclaimer may also arise from an applicant’s statements in a parent patent application if the parent application relates to the same subject matter as the claim language at issue.” The effect of the disclaimer is not negated either by the abandoned status of the parent application or “[t]hat the examiner did not rely on these statements, as the parent application never issued.”

Thus, the Court affirmed the claim construction, noting “[i]n light of these statements during prosecution, RFID Tracker cannot now contend that the claimed interrogator/reader is anything more than ‘simply a receiver and a field generator in its simplest form.’”