Pursuant to section 39 of the Patents Act, the extent of the protection conferred by a patent is determined by the patent claims. The description may serve as a guide to the understanding and interpretation of the patent claims. Norwegian Law provides for protection by equivalence. Following the Supreme Court’s decision in the so-called Donepezil Decision from 2009, the conditions for protection by equivalence under Norwegian law, may be summarized as follows: First, the alleged infringing product or process must solve the same problem as the patented invention, second, the modifications made must have been obvious to a skilled person and third, the alleged infringing product or process must not belong to the prior art. With respect to the second condition it is not sufficient for determining infringement by equivalence that the modifications are obvious to the skilled person (based on the inventive step standard). According to the abovementioned Donepezil Decision, it is an additional requirement that the modifications are so close to the solution in the patent claim that it is fair to characterize the modification as “reasonably identical” to that solution.
Even though all of the abovementioned conditions are fulfilled, other circumstances may prevent the finding of infringement by equivalence. The prosecution history is the most important example of such circumstances that may exclude the finding of infringement by equivalence.
The prosecution history’s relevance for both the interpretation of patent claims and the assessment related to determining the patent’s scope of protection is undisputed under Norwegian patent law.
Furthermore, the prosecution history may generally have a greater impact on the assessment of infringement by equivalence than for direct infringement.
It is first and foremost the consideration of third parties that speaks in favour of emphasizing the prosecution history. As a general guideline, protection through the application of infringement by equivalence should be denied where the prosecution history gives a third party legitimate reason to assume that the intent was to waive protection for the disputed embodiment. If the applicant has previously limited the claims to stay clear of the state of art, this may give third parties the impression that the applicant has waived the embodiments which the limitation intended to exclude. Furthermore, if the applicant during prosecution expressly waived certain embodiments, he cannot reasonably claim that these should later be within the scope of protection through infringement by equivalence.