An approach to the doctrine of equivalents: Amending claims of patent applications

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The impact that amendments applied to the claims of a patent application during prosecution may have in a subsequent infringement litigation has been largely debated in the last few years. In the following paragraphs, the recent developments that have occurred in Europe are compared to the practice that appears to be established in the USA.

In Decision N. 54470/2016 (10 September 2017), the Milan Court ruled that if a patent undergoes substantive amendments – that is, amendments introducing new features which are based on the description – the doctrine of equivalents should not apply to those features. This decision appears to be consistent with the practice of the Courts in the USA.

Similar decisions were taken in Germany and UK, but they were later reversed by the respective supreme courts, with decisions X ZR 29/15 (14 June 2016) and [2017] UKSC 48 (12 July 2017), respectively.

A patent system must ensure a fair balance between the right of the inventor to enforce his patent rights and the need to guarantee legal certainty for third parties. This concept is established in Art 52 of the Italian patent law (CPI – Industrial Property Code) and has corresponding provisions in the patent law of other countries.

In this context, the application of the doctrine of equivalents is an important advantage for the patentee. When assessing whether this advantage is unfair or inappropriate in the case of substantial amendments, one should consider the other factors that deeply impact the legal certainty for third parties: (i) the prohibition against broadening the scope of protection with a post-grant amendment, established for example by Art 76(1)(c) CPI and Art 123(3) EPC, and (ii) the prohibition against adding fresh subject matter in any amendment, with respect to the content of the application as filed, established for example by Art 76(1)(c) CPI and Art 123(2) EPC.

Regarding the first factor, the prohibition against broadening the scope of protection with a post-grant amendment determines that, once a patent is granted, competitors will have the possibility of studying the claims and may rest assured that, if their technical solution falls outside the scope of the independent claims of the patent, they cannot be later be found to have infringed the patent.

Regarding the second factor, the harshness of the criterion for establishing whether or not an amendment has enough basis in the description may vary greatly from one country to the other. Typically, in Europe the freedom for a patentee to amend claims based on the description is severely limited with the aim of ensuring legal certainly for third parties. However, the situation is quite different in the USA, where applicants have plenty of freedom to fine tune their claims in order to overcome prior art cited against the patent.

Let us also consider the situation where the need arises for a patentee to amend claims in the post-grant stage. Typically, such a need is generated by opposition proceedings before the EPO or by a nullity action brought against the patent, often as a counterclaim. Under these circumstances, the patent is ordinarily challenged on the ground of prior art that the Examiner did not consider, as a result of which the patentee did not have a chance to amend his patent during the Examination phase (in the absence of a prohibition against broadening the scope of the patent) in order to address such references.

Therefore, the need to resort to the description to limit claims is often a reaction to a situation the patentee has not faced before (sometimes also because of the limits of the patent offices concerned), rather than abusive behavior.

Also, the stricter the criterion for assessing new subject matter in an amendment, the more probable it is that additional features will have to be introduced into the claim, in addition to those strictly needed to actually meet the requirements of novelty and inventive step with respect to a (new) reference.

For the above reasons, it appears that the application of the doctrine of equivalents also to features that are possibly added in the course of description-based amendments is important to preserve a fair right for an inventor to protect his invention.

Conversely, should the doctrine of equivalents be excluded from all post-grant limitations added based on the description, a risk appears to arise of an excessive advantage for third parties, who could oppose a patent by resorting to a tactical use of prior art which was unknown to the applicant during the prosecution of the patent application, thus unbalancing the patent system against the patentee. In other words, a risk of an unbalanced and weakened patent system would arise, with all of the consequences that this could bring about.