Canada: ArcelorMittal And The Federal Circuit: When Is Re-Issue Broadening?

Last Updated: May 21 2015
Article by Ken Bousfield

ArcelorMittal v. AK Steel, Fed. Cir. May 12, 2015

ArcelorMittal's US patent 6,296,805 had been judicially interpreted by the US Court of Appeal for the Federal Circuit.1 The patentee thereafter sought, and obtained, a re-issue, RE 44,153. It was filed more than two years after the original grant, and so it was necessarily a narrowing re-issue. In the re-issue the patentee added two dependent claims. Although the claims were narrowed in terms of form, the substantive effect of the dependencies was to force a broader interpretation of the independent claim than had been made by the Federal Circuit.

The defendants sought a declaration of invalidity of RE 44,153 as an impermissible broadening outside the statutory two year period. US Delaware D.C. granted summary judgement. ArcelorMittal appealed. ArcelorMittal argued that the new interpretation by the PTO was new evidence to support reconsideration of the previous claim interpretation.

The Court held that under the "law-of-the-case" doctrine2, the re-issue was not new evidence, and that the previous interpretation should continue to govern. The Court had already interpreted the claim language. The introduction of the dependent claims after-the-fact could not alter the previous interpretation. The Court repeated the rule that, under the statute, the issue of broadening is decided by determining whether the new interpretation of the claim in question would encompass more than it had done before re-issue, notwithstanding that the wording of the independent claim might not have changed on its face.

The Court upheld the validity of the two newly introduced dependent claims, nonetheless, as they had not been previously interpreted. This leaves open the possibility that had the re-issue been filed before interpretation in the first case, there might have been a different result.

The underlying practice point may be one of considerable subtlety in both re-issue and re-examination.

For example, a patentee may become aware of a possible infringer. However, the pertinent broad claim may be subject to more than one interpretation – one infringing, the other not infringing. Alternatively, the patentee may have become aware of prior art. Under one interpretation the claim is valid, under another the claim is invalid.

Alternatively, it may be the specification discloses only a single embodiment, Y. The competitor's apparatus includes feature Z. Feature Z might itself be inventive, and may not have been known when the case was filed. Under a fair reading of the broadest remaining allowable claim in the patent, an apparatus using feature Z might not necessarily infringe.

In those circumstances, use of re-issue or re-examination to introduce a new dependent claim with feature Y – which the accused apparatus plainly does not include – may cause an interpretation of the independent claim as necessarily including species of the invention employing Y or features other than Y, i.e., Y or Z, and perhaps other features V or W, too.

That is, addition of dependent claims is allowed in both re-issue and re-examination: they must inherently be narrowing. The Doctrine of Claim Differentiation3 may then be a lever to yield a broader interpretation of the other claims. Where the new dependent claim recites that "said feature X [a genus term] includes a Y [a species term]", under the Doctrine of Claim Differentiation the claim from which the newly added claim depends must also include species other than species limited to feature Y.

The use of new dependent claims and the Doctrine of Claim Differentiation to obtain broader interpretation of existing claims has been criticised.4 It can be seen as an attempt improperly to extend claim scope. However, it is axiomatic of peripheral claiming that enabling disclosure of a single species is always sufficient support for a claim to the genus. Unless there is prior art, the claim to the genus will be valid. The supposed "broadening" can occur only if the subject matter falling within the "broadening" is itself new, useful, and unobvious. A narrow interpretation of the independent claim implies that while there was subject matter that could have been claimed, the inventor failed to do so.

So, is the issue criticism of impermissible broadening, or a complaint that the patentee failed to give a large enough windfall to the public? In context, "the public" may tend to be the patentee's competitors. While public notice is important, and the onus is on the patentee to draft clear claims, a narrow interpretation that deprives the patentee of property is a windfall to volunteers who might otherwise be infringers. It used to be that equity would not aid a volunteer.

In ArcelorMittal, the Federal Circuit indicates that the question is always: What is the correct interpretation of the claim? Characterisation of the practise of ex-post addition of dependent claims as impermissible broadening presumes a conclusion of law; and may be pejorative. It may be that the further dependent claims do focus interpretation of the broad claim on the correct meaning. If so, the amendments are genuinely directed toward permitting the inventor to protect that which he or she has in good faith invented – the purpose of re-issue since 1832.


1. ArcelorMittal Fance v. AK Steel Corp. 700 F.3d 1314 (Fed. Cir. 2012)

2. A court will not consider an issue it has previously decided other than under the exceptional circumstances of (a) the subsequent availability of substantially different evidence; (b) when a subsequent controlling authority changes the law; and (c) where the decision is clearly erroneous.

3. Each claim in a patent defines a monopoly of different scope. Therefore if a dependent claim recites X, there is a strong presumption that the claim from which it depends encompasses at least some integers that are "Not-X". See SRI Int'l v. Matsushita Elec. Corp. 775 F.2d 1107 (Fed. Cir. 1985): "It is settled law that when a patent claim does not contain a certain limitation and another claim does, that limitation cannot be read into the former claim in determining either validity or infringement." See also SunRace Roots Enterprises Co. v. SRAM Corp. 336 F.3d 1298, 1303 (Fed. Cir. 2003); and Retractable Technologies v. Becton Dickinson, Fed. Cir. July 8, 2011.

4. Mark A. Lemley, The Limits of Claim Differentiation, 22 BTLJ Article 4, September 2007.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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Ken Bousfield
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