Application of doctrine of equivalents to range limitation in claim does not vitiate the limitationNovember 5, 2007

In a decision Friday, the Federal Circuit affirmed a district court's claim construction, but reversed its rulings regarding the sufficiency of notice of infringement and the applicability of the doctrine of equivalents.

Regarding sufficiency of notice under 35 U.S.C. 287(a), the court held that while the patentee did not mark its products, its notice of infringement via letter was sufficient where the patent holder's identity is accurately noted on the patent included with a notification letter, even if not included in the text of the letter itself.

The court also held that the doctrine of claim vitiation does not necessarily preclude application of the doctrine of equivalents when the claim language includes a range of values. The fact that the equivalent would fall outside the range specified in the claim does not necessarily mean the limitation would be vitiated.

More detail of U.S. Philips Corp. v. Iwasaki Elec. Co. after the jump.

In this case Philips alleged that Iwasaki infringed a patent relating to high pressure mercury vapor discharge lamps which are designed to have "an improved color rendition and a longer life." A limitation of the claims was that the lamp was filled with a gaseous mixture in which "at least one of the halogens Cl, Br, or I is present in a quantity between 10-6 and 10-4 µmol/mm3.

Prior to the lawsuit, the intellectual property division of Philips sent a cease and desist letter to Iwasaki. The letter did not disclose the relationship between the subsidiary and the parent company (which held the patent), did not disclose that U.S. Phillips was the patent holder. The letter did include a copy of the patent as well as an offer for a non-exclusive license. U.S. Philips did not mark their lamps as patented.

Three issues were raised on appeal. The first was whether or not the district court erred in determining that Philips' cease-and-desist letter did not gave Iwasaki sufficient notice of infringement under 35 U.S.C. 287(a). The second was whether or not the district court's interpretation of the claims, essentially limiting the range from 1 x 10-6 to 1 x 10-4, was accurate. The third issue was whether the district court was incorrect in determining that the use of a numerical range in a claim precluded Philips from alleging infringement under the doctrine of equivalents.

The district court had concluded that the cease-and-desist letter did not provide proper notice of infringement as the letter was not sent by, and did not reference, the patent owner U.S. Philips. The Federal Circuit disagreed, finding that the text of the letter, combined with the accurate ownership information on the enclosed patent fulfilled the reasons for strictly enforcing the notice requirement as the party sending the letter was the party "to contact about an amicable and early resolution of the potential dispute, to consult with about design changes to avoid infringement, and with whom to negotiate a valid license." Based on this finding the court held that "when the information printed on the patent is correct, it is enough to put an accused infringer on notice of the patentee's identity."

Regarding the numerical range, at the district court and on appeal Philips argued that the use of the terms 10-6 and 10-4 each indicated a number less precise that 1 x 10-6 and 1 x 10-4 respectively, specifically numbers which, when rounded, would result in these endpoints of the range. The Federal Circuit, consulting the specification, determined that the context of the patent did not provide any support for the numbers to be less precise than they were construed by the district court judge. The Federal Circuit rejected Philips' argument stating that "the overall phrase 'a quantity between ____ and ____ ' is a construction that implies a specific range. It does not imply a range between two values which are themselves ranges." (internal citations omitted).

The final issue decided by the court was whether or not the use of ranges in the claims precluded the application of the doctrine of equivalents. The argument was that applying the doctrine of equivalents to a claim with a range vitiated the claim limitation by allowing infringement outside of the range specified in the claim. The district court held that claim vitiation applied, and refused to consider infringement under the doctrine of equivalents. The Federal Circuit noted that "a holding that the doctrine of equivalents cannot be applied . . . is nothing more than a conclusion that the evidence is such that no reasonable jury could conclude that an element of an accused device is equivalent to an element called for in the claim." The court then determined that a reasonable jury could conclude that the use of a value slightly outside of the range specified in the claim infringed under the doctrine of equivalents, and therefore the limitation would not be vitiated by application of the doctrine.

To read the full decision in U.S. Philips Corp. v. Iwasaki Elec. Co., click here.

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