The doctrine of equivalents allows to broaden the scope of claims to encompass products or processes that do not fall within the literal scope of a patent claim but are nevertheless equivalent to the claimed ones; its purpose is to promote fair patent coverage so that trivial departures from the claim language cannot be used to avoid infringement.

The doctrine of equivalents allows patent proprietors to succeed in a patent infringement trial even if a disputed item (apparatus or process) does not fall within the literal scope of the claims; unfortunately, this can make the scope of protection ambiguous causing a conflict between the rights of the patent holder on the one hand, and the right to legal certainty of third parties on the other.

However, there is not yet a single criterion for applying the doctrine of equivalents in all states, and there are differences even between European countries, thus the scope of validation patents stemming from a same European patent may be determined differently by different national Courts.

Over the years, tests have been developed to evaluate whether a disputed item falls within the scope of a claim through the application of the doctrine of equivalents.

In this paper, the author Gaetano Barbaro first explores the logical implications of certain requirements that a test should have to assert or deny the presence of infringement in cases where the doctrine of equivalents is applied, and then derives criteria from these requirements to suggest a new test that can be used at trial.

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This article is a translation of a pre-print of the article published in Italian by “Rivista di Diritto Industriale“, n°2, 2025, p. 86-100