Legal precedents show that the issues of equivalency are not considered in validity disputes unlike in patent infringement disputes.
Author of the publication, Aleksey Zalesov, provides a critical analysis of the opportunity to use the outdated legal acts in order to justify the equivalency of features, as well as the use of features and conditions that are not relevant of the essence of the issue in question. Reviewing the common existing approaches to defining equivalent attributes, the author states that equivalency should be treated as a question of law and not a fact. Then the author suggests the criteria for defining equivalent features considering technical rules and circumstances of the patent dispute in question.