Reeling in the Doctrine of Equivalents

In Olaf Sööt Design LLC v Daktronics Inc 2020-1009, 2020-1034 one of the Court of Appeal for the Federal Circuit (CAFC) Judges expressed concern about the misuse of the doctrine of equivalents and sought to reaffirm the primacy of the claims in determining the scope of a patent’s monopoly.

The case involves an appeal of a District Court decision in which Daktronics were denied a judgment as a matter of law (JMOL) motion after the jury had found that Daktronics device contained the disputed elements of a claim on a doctrine of equivalents basis and so infringed Olaf Sööt’s patent.

The patent concerns a theatre winch for moving scenery and lighting by winding and unwinding cables, which are attached to the scenery, around a hollow drum. The winch is configured such that the cables wind and unwind together without tangling and are maintained perpendicular to the drum which rotates in relation to a fixed screw, whereby the drum and a hollow hub move laterally such that they surround some of the screw. This configuration both gives some protection to the screw and reduces the overall length of the winch. Only claim 27 was in issue, the claim having integers (a) – (h), with the District Court jury having found that integers (b), (d), (e) and (h) were in Daktronics device on a doctrine of equivalents basis.

The unanimous decision delivered by Circuit Judge Proust firstly found that the District Court had erred in leaving it to the jury to resolve a fundamental dispute over claim scope as that is one of the Court’s roles. With integer (h) of claim 27 there was a dispute as to whether the hub is part of the drum given that in Daktronics device the hollow hub, but not the drum, can surround some of the screw during the winding motion. Integer (h) states:

(h) said hollow hub and hollow drum being sized such that the screw can move into the hollow hub to allow the hollow drum to receive the screw as the cable unwinds from or winds up on the drum as the object moves to its respective down or up position.

The jury found that the hub was part of the drum, and in its post-jury verdict denying Daktronics JMOL motion the District Court also found the hub to be part of the drum.

The CAFC reversed that claim construction, finding that the claim language treats the hub and drum as two separate components meaning that the hollow hub is not part of the hollow drum. While the movement of the screw into the hollow hub allows the hollow drum to receive the screw the CAFC found this to show that the hollow hub is facilitative with respect to the hollow drum but not that it is part of the hollow drum.

Olaf Sööt had sought to justify its construction by referring to integer (e) which recites “said drum having at a first end a hollow hub …”, however the CAFC found this to merely specify that the hollow hub is positioned at one end of the hollow drum. Further, while the specification notes that the hub and drum components can be welded together, the CAFC found this to be permissive rather than mandatory.

Given its finding that the hollow hub is not part of the hollow drum and given that with the Daktronic device the screw is not received by the hollow hub the CAFC concluded as a matter of law that the Daktronic device does not infringe under the doctrine of equivalents.

Circuit Judge Lourie delivered a concurring opinion in order to express concerns about how the doctrine of equivalents is being utilised. Judge Lourie emphasised that the doctrine of equivalents is an exception to the primary principle of literal infringement of the patents claims and should at most and only rarely be applied in relation to two integers of a claim, not four as occurred in the District Court. Equivalence requires meeting either the function-way-result test or the insubstantial difference test in a way that does not eliminate altogether the claimed element. Judge Lourie emphasised that applying these tests requires the exercise of common sense as there can be instances where something can satisfy the tests, yet clearly not be an equivalent. Further, where there are multiple claim elements that do not literally infringe, then that should indicate the patent’s claims have been invented around or otherwise avoided, which has publically desirable pro-competitive effects. Judge Lourie considered that taking the contrary view makes a mockery of the primary role of claims, which will cease to serve their intended purpose if the doctrine of equivalents is applied too liberally.

When the UK Supreme Court extended the patentee’s scope of protection by allowing for a doctrine of equivalents in its Activis UK Ltd v Eli Lilly and Co [2017] UKSC 48 decision it also placed it as an exception to the rule of “normal” interpretation - which the Court of Appeal in Icescape Ltd v Ice-World International BV [2018] EWCA 2219 at [60] subsequently clarified means a purposive interpretation. It is only after establishing that there is no "literal" infringement in accordance with the three reformulated Improver questions that the Supreme Court’s three stage test for infringement by way of immaterial difference is applied. Namely:

1. Notwithstanding that it is not within the literal meaning of the relevant claim(s) of the patent, does the variant achieve substantially the same result in substantially the same way as the invention, i.e. the inventive concept revealed by the patent?
2. Would it be obvious to the person skilled in the art, reading the patent at the priority date, but knowing that the variant achieves substantially the same result as the invention, that it does so in substantially the same way as the invention?
3. Would such a reader of the patent have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the relevant claim(s) of the patent was an essential requirement of the invention?

While not specifically addressed in the Supreme Court’s decision the above questions contemplate a single variant and would be consistent with Judge Lourie’s disdain for finding infringement where there are multiple variants. Also, the above questions seek to give effect to the proviso in Article 1 of the Protocol on Interpretation of Article 69 (EPC 1973 or 2000) that the claims should not serve only as a guideline, which is consistent with the limited ambit that Judge Lourie considers is available under the doctrine of equivalents. Nonetheless, as in the USA, the UK Supreme Court found that there is a place for the doctrine of equivalents and that it should have played a role since the introduction of the Protocol on Interpretation of Article 69.

Author: Quinn Miller

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