The Federal Circuit recently reversed a decision of the United States District Court for the Easter District, overturning an award of damages and decision of infringement in a case between rival boat makers, Brunswick Corp. and Cobalt Boats. In doing so, the Court decided that the claims included precise values without any qualifying terms, and thus, the language should be construed and interpreted as imposing a "strict numerical boundary". In the case, this was not met.
Cobalt owned a patent on a retractable swim step for boats, U.S. Patent No. 8,375,880. The patent included two claims that were found to be infringed by Brunswick, claims 4 and 5. Claim 4 depended from Claim 1, which was found to be invalid. Claim 1 was directed toward a retractable step and included that the step "capable of being rotated 180°". Claim 5 was directed toward a deployable swim step and included "coupling means configured to permit rotation of said step 180°". Brunswick's allegedly infringing device included a step that was agreed to be rotated between 172-179°. The District Court held that this was within the construct of the claim term of 180°, but the Federal Circuit disagreed.
Cobalt argued that the term "180 degrees" essentially means "flipping over". The Court disagreed. There was no use of "about" or any other qualifying language before the 180-degree language. The Court stated, "Where a precise value is included in the claim without a term such as 'about', we interpret the claim language as imposing a strict numerical boundary, absent evidence that such a construction would be inconsistent with the intrinsic evidence". There was no intrinsic evidence that changed this view, and therefore, the Court held that "180 degrees" requires that the swim step be capable of rotating at least 180 degrees, and a step that can rotate at most 179 degrees would not meet the limitation, while a step that can rotate 181 degrees would. As Brunswick's step was limited to rotate between 172 and 179 degrees, there could be no literal infringement.
The Court then went on to evaluate the claims and Brunswick's view of the doctrine of equivalents. As a reminder, "The doctrine of equivalents allows the patentee to claim those insubstantial alterations that were not captured in drafting the original patent claim but which could be created through trivial changes". Festo Corp. v. Sho-ketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 733 (2002). However, the doctrine of equivalents is limited by prosecution history estoppel, which "precludes a patentee from regaining, through litigation, coverage of subject matter relinquished during prosecution of the application for the patent".Id. at 734 (brackets omitted) (quoting Wang Laboratories, Inc. v. Mitsubishi Elecs. Am., Inc., 103 F.3d 1571, 1577 (Fed. Cir. 1997)).
In the present case, the "180°" language was added during prosecution to overcome a rejection (a step that was rotated 90°), and Cobalt argued this was only to distinguish the exact art cited against the claims, and that was only what was surrendered. The Court disagreed, and stated, "the scope of disclaimer is measured by the difference between the original and the amended claims, not the difference between the amended claims and the prior art that was avoided through the amendment…In particular, when claims are amended to include a specific numeric boundary, we have held that the patentee cannot later recapture what is beyond that boundary through the doctrine of equivalents." As such, the claims required rotation of at least 180°, which was not met by the Brunswick step, and therefore, there was no infringement under the Doctrine of Equivalents either.
Some key takeaways from the case are to take care when amending claims to include values so as to not unduly limit the scope of the protection. Ranges, use of broadening qualifiers (about, substantially, etc.), and amending to limit only to overcome the rejections are ways to attempt to keep broad claims from being narrowed and scope surrendered. Working with your attorney to determine the best way to overcome without unduly narrowing requires effective and open communication between parties and can provide numerous advantages during enforcement.