On October 30, 2009, in Ex parte Senju Metal Industry Co. the Board of Patent Appeals and Interferences (“BPAI”) affirmed a rejection of non-original patent claims in a reexamination proceeding directed to soldering flux for soldering elements. As a predicate to its decision, the BPAI explained the rationale behind application of the broadest reasonable interpretation rule in administrative proceedings within the USPTO. “This longstanding principle is based on the notion that ‘during patent prosecution when claims can be amended, ambiguities should be recognized, scope and breadth of language explored, and clarification imposed.’ That is, a patent applicant has the opportunity and responsibility to remove any ambiguity in claim term meaning by amending the application. ‘Only in this way can uncertainties of claim scope be removed, as much as possible, during the administrative process.’ ‘[A]s applicants may amend claims to narrow their scope, a broad construction during prosecution creates no unfairness to the applicant or patentee.'”. During the reexamination proceeding the patent examiner determined that the claim term “volatile organic solvent conventionally used in a soldering flux” failed to meet the definiteness requirement of 35 U.S.C. §112, 2nd paragraph because the description of the invention did not recite this language, “let alone any disclosure that would enlighten one skilled in the relevant art as to what solvents are covered by the [term].” The appellants in an effort to overcome the rejection filed a declaration averring that a person skilled in the relevant art would understand “volatile” to mean “evaporating or passing off readily in the form of a vapor and that solvents in the [patent at issue] fall under this definition.” Appellants argued that “[o]ne skilled in the art of preparing soldering fluxes would understand what solvents are conventionally used in soldering flux.” Agreeing with the patent examiner, the BPAI observed that the limitation “volatile organic solvent” cannot be found in the patent specification. Also the appellants used the term in a “manner contrary to the ordinary meaning of the term” urging that ethylene glycol, which has a boiling point of 197°C, is covered by the claim. The BPAI then held that the “use of terms contrary to their ordinary meanings, in and of itself, does not render a claim indefinite, for [p]atentees are free to act as their own lexicographers … one skilled in the relevant art would not be able to ascertain whether an organic solvent with a boiling point of, e.g., 200°C would be covered by the disputed claim terms.” The BPAI determined that the specification “does not reasonably apprise the full scope of what Patentees mean by ‘volatile organic solvent conventionally used in a soldering flux.'” Compare this decision with the our November 18, 2009 posting Attacking a Patent in Reexamination for Lack of Written Description and Enablement?