Establishing the boundaries of protected inventions determines the actual scope of the rights conferred by a patent147, and is particularly important for some health-related inventions. It is a matter of national legislation to define when products or processes that are not literally described in a claim may be deemed “equivalent” and therefore considered as infringing on the patent rights.
147 See e.g., Takenaka, 1995.
There are different approaches to deal with this issue148. Under one approach, equivalence may be found if the allegedly infringing variant of a process or product performs substantially the same function in substantially the same way to obtain the same result. Another approach relies not on a functional analysis, but on an objective comparison of the elements that constitute the variant and the invention, and particularly on the extent to which the variant introduced by the potential infringer may be deemed obvious149 by the skilled person in the light of the claimed invention. This latter approach may permit an adequate protection of the inventor’s interests, while leaving more room for third parties’ innovations in the field covered by the patent.
148 See, e.g., Franzosi, 1996; Schuster, 1996; Anzalone, 1996. An example of the application of the doctrine of equivalents is provided by a case decided by the Osaka High Court on May 9, 1996. Sumitomo (Japan) had argued that it had independently developed a different form of t-PA, which had been previously patented by Genentech (USA). Sumitomo’s t-PA differed from Genentech’s in relation to the 245th position of the aminoacids sequence. This difference was regarded by the Court as insufficient to avoid infringement since, despite that difference, Sumitomo’s product was equivalent to Genentech’s t-PA.
149 The date at which the equivalence is considered may be the filing date of the application or the date of infringement.
EQUIVALENCE TEST IN THE UNITED KINGDOM
The United Kingdom employs a three-part equivalence test, established by Hoffman J. in Improver Corporation v Remington Consumer Products Ltd  FSR 181: “If the issue was. whether a feature embodied in an alleged infringement which fell outside the primary, literal or acontextual meaning of a descriptive word or phrase in the claim (“a variant”) was nevertheless within the language as properly interpreted, the court should ask itself the following three questions:
(1) Does the variant have a material effect upon the way the invention worked? If yes, the variant is outside the claim. If no
(2) Would this (i.e. that the variant had no material effect) have been obvious at the date of publication of the patent to a reader skilled in the art? If no, the variant is outside the claim. If yes -
(3) Would the reader skilled in the art nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention? If yes, the variant is outside the claim.”
There is no rule in the TRIPs Agreement determining how narrow or broad the “doctrine of equivalence” should be, leaving this issue to national legislation.
In general, less technologically advanced countries may be expected to favour a narrow doctrine of equivalents, which is more pro-competitive and stimulates applications by those who work around patented inventions. In developed countries, such as in the United States, there are also open questions about the desirable scope of that doctrine; many think that a narrow doctrine of equivalents is required to promote innovation150. Country preferences relating to the doctrine of equivalents may also depend on a country’s pharmaceutical, chemical, and biotechnology development and manufacturing capacity, and on the availability of alternative forms of protection for local innovation.
150 See, e.g., Merges, 1992, p. 705.