Contributed by Jim Nelson, J.D., Ph.D. of Schwegman Lundberg & Woessner, P.A.
The Siemens Medical Solutions USA, Inc. v. Saint-Gobain Ceramics & Plastics, Inc., (a copy is available at the end of this post) case presents a fundamental issue and holding about equivalents in the face of a patent covering the product alleged to infringe another patent under the DOE.
The Court said that an equivalent of the claims at issue is present even though that equivalent was literally claimed in another patent. Of course that holding tracks the rule we all have learned: domination. You can patent an improvement of an earlier patented invention but your patent will be dominated by that earlier patent. Usually, this domination rule is considered in terms of literal infringement, not doctrine of equivalents.
In this situation, the defendant offered a clever retort to the domination rule. The defendant said that because of the relation among equivalents, obviousness, the later patented product, the plaintiff needed to show equivalents by a higher degree of proof, clear and convincing evidence, not preponderance of evidence. The defendant based its argument upon the theory backed by case quotes such as that from Judge Nies: a substitution in a patented invention cannot be both nonobvious (leading to a patent on the substitution) and insubstantial (leading to infringement under DOE).
The majority of the Court disagreed. They said that obviousness is not tantamount to equivalents.
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