The Meaning Of 'At Least 1 Of A And B' At PTAB

By Braden Katterheinrich and Nick Anderson (July 27, 2018, 1:10 PM EDT) -- In a decision recently designated as "informative" and originally published in March 2017, the U.S. Patent and Trademark Office's Patent Trial and Appeal Board discussed proper interpretation of the phrase "at least one of [A] and [B]" for the purposes of examining patent application claims. The board's decision in Ex parte Jung[1] highlights potential issues with use of the phrase "at least one of A and B." Namely, the phrase is subject to three different interpretations of widely varying scope. These interpretations include a disjunctive list of mutually exclusive alternatives (i.e., either A or B but not both), a disjunctive list of nonmutually exclusive alternatives (i.e., A or B, or A and B), and a conjunctive list requiring multiple items (i.e., at least one of A and at least one of B, but not either A or B)....

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