Intervening Rights Do Not Protect Accused Patent Infringer Despite Amendment During Reexamination

The Federal Circuit recently provided a refresher lesson about intervening rights, particularly about what sources of evidence the court may find persuasive, in Convolve, Inc. et al. v. Compaq Computer Corp. et al., No. 2014-1732 (Fed. Cir. Feb. 10, 2016). At least in this case, the court weighed evidence from the original examination of the patent more heavily than evidence from the reexamination when applying the test for intervening rights.

Intervening rights protect accused infringers when a patentee amends a patent in a reexamination proceeding. See 35 U.S.C. § 252. The test is whether the scope of the claims changed during the reexamination: for the patentee to collect damages for infringement occurring before the reexamination, the scope of the claims before the reexam must be identical to the scope of the claims after. The court reiterated, however, that the test is substantive. The language of the claims may change so long as the substantive scope does not.

In the reexamination for U.S. Patent No. 6,314,473, the language did change. In response to an obviousness rejection, Convolve, the patentee, amended the term “acoustic noise” to “seek acoustic noise.” The examiner had treated “acoustic noise” under the broadest reasonable interpretation as encompassing both types of noise afflicting hard drives, noise from the spindle and noise from seeking. Both the examiner and Convolve called the amendment “clarifying,” and the examiner withdrew a prior art rejection after the amendment.

The Federal Circuit panel, however, decided that “acoustic noise” had always been limited to seek noise. The panel acknowledged that the term “seek acoustic noise” did not appear in the specification and that the plain meaning of “acoustic noise” covered both types. But the panel gave more credit to the problem that the patent solved. The specification focused solely on mitigating noise caused by seeking, and limitations in the claims involved modifying the “seek time” and the “seek trajectory shape.” Moreover, Convolve had overcome a rejection during the original examination because the prior art reference addressed spindle noise. Because the scope of the claim term remained constant through the reexamination, intervening rights did not protect the defendants, Compaq and Seagate.

The most interesting takeaway? How little credit the panel gave the reexamination examiner. “[T]he examiner focused exclusively on the language of the claims at the expense of the clear language in the specification and prior examination history ... and expressly rejected the patentee’s attempt to interpret the claims in light of the specification.” After thus taking the examiner to task, the panel felt no need to follow the assumptions made by the examiner even though those assumptions had been echoed by the patentee, as the panel “decline[d] to give significant weight to the patentee’s … use of the term ‘clarify’ or ‘clarifying’ in describing the amendment in prosecution.”