1 April 2011Jurisdiction reportsGábor Harangozó

Doctrine of equivalence

This doctrine expresses that when determining the scope of a patent (or utility model), a claimed feature may be replaced by a different one that performs the same or substantially the same function in the same or substantially the same manner with the same or substantially the same effect. In a recent utility model case, the Metropolitan Appeal Court explained that equivalency may not be extended to features that were not available before the priority date due to the lower level of the state of the art.

Another common interpretation of the doctrine of equivalence also widely used in litigation cases is that by replacing a claimed feature with an equivalent feature, the scope of a patent (or utility model) may not be extended so that prior art solutions fall into the scope of the patent (or utility model) concerned.

This limitation seems to be somewhat softened, at least in view of a recent opinion of the Industrial Property Expert Board of the Hungarian Intellectual Property Office in connection with a patent infringement case. The expert board has no decisive role in patent infringement litigation proceedings before the courts; however, its position can be taken into account by the court and parties often like to request such an opinion before or during the lawsuit.

In this case, all of the claimed features of the patent except one appear to be embodied in the allegedly infringing device. The plaintiff stated that the single different feature of the injuring device is equivalent to a corresponding claimed feature. However, the defendant disputed the equivalency and also cited prior art documents showing a similar prior device wherein disputed features can be found in the same form as used in the device of the defendant.

In the meantime, the defendant requested that the expert board determine whether the doctrine of equivalence may be limited in a way that a similar solution comprising an equivalent feature is considered outside the scope of the patent if that solution had already been disclosed in a prior art document.

“Until the patent is revoked or limited, the patentee is entitled to enforce its patent rights without any limitation, even if patentability of the invention is highly doubtful.”

The expert board declared that the absolute limitation cannot be used in the interpretation of the doctrine of equivalence, pointing out that applying such a limitation to the equivalence in patent infringement proceedings, for example, would prohibit the interpretation of the scope of the patent in those areas where no patent could have been granted for the invention. Hungarian patent law does not specify any necessary relationship between the scope of the invention and patentability of the invention.

A patent in force enjoys a presumption of patentability and this presumption can be destroyed only in a revocation procedure. Until the patent is revoked or limited, the patentee is entitled to enforce its patent rights without any limitation, even if patentability of the invention is highly doubtful. The scope of the patent is always to be determined according to the claims, which should be interpreted on the basis of the description and the drawings.

When determining the scope of the patent, using either a literal interpretation of the claimed features or the doctrine of equivalence, a possible lack of patentability [of the characteristic alone] cannot be considered as an absolute limitation for the scope of the patent in those areas to which the scope can be extended on the basis of the claim’s interpretation.

Consequently, according to the expert board, by replacing a claimed feature with an equivalent feature known per se prior to the priority date of the ruling patent, the scope of a patent (or utility model) may be interpreted in such a way that a characteristic belonging as such to the prior art can be involved as an equivalent characteristic in the disputed case.

This is a broader interpretation of what was used earlier. As the validity of a patent cannot be questioned in a patent infringement lawsuit, if the defendant feels that this broadening has brought about validity problems, this can be examined in a separate nullity proceeding.

Whether or not the board’s interpretation will be accepted by the court in the pending patent infringement lawsuit is, however, still an open question.

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