Gaby Longsworth, Ph.D. and Chenghua Luo, Ph.D. note that courts have formulated several tests for the determination of equivalents. In the past, decisions from the U.S. Court of Appeals for the Federal Circuit appeared to indicate that the doctrine of equivalents does not capture subject matter that the patent drafter reasonably could have foreseen during the application process and claimed. However, in a recent decision Ring & Pinion Serv. Inc., v. ARB Corp. Ltd., No. 2013-1238 (Fed. Cir., February 19, 2014), the Federal Circuit departed from this line of reasoning and held that foreseeability of an equivalent at the time of patenting is not a bar to a finding of infringement under the doctrine of equivalents. This article in the March 2014 issue of the Maryland State Bar Association Bar Bulletin discusses this topic in more detail.

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