The Federal Circuit’s recent decision in In re Chudik, Appeal 2016-2673 (Fed. Cir. August 25, 2017) (non-prec.), offers patent practitioners a cautionary tale and good teaching points about the propriety of negative limitations and functional claim language.  No two situations are the same, of course, but the case offers a real-world example of how claims reciting these types of features may be assessed by the Patent Office and the Federal Circuit. 

Dr. Chudik’s application concerns a humeral implant used in shoulder replacement surgery.  The main application claim addressed on appeal recites a humeral implant that includes “a humeral surface component having a non-articular surface configured for long-lasting fixation of the implant on a humeral head and no stem.” Drawings in the application show a humeral implant having a humeral surface shaped to match the anatomy of the humeral head and a separate stem, and the application describes the stem as a physically distinct and separate component from the implant. The Patent Office rejected that claim over a prior art reference that describes a glenoid implant.  Figures in that prior art reference show an implant that includes a slightly curved platen having a portion that juts outward from its main body to engage a base.

On appeal, Dr. Chudik argued the prior art reference could not anticipate because its outwardly-jutting platen portion was a stem. Dr. Chudik’s rejected claims, he argued, expressly state that the humeral surface component has “no stem.”  The Federal Circuit rejected his argument, concluding instead that the prior art’s outwardly-jutting platen portion was not a stem because it was “part of and not separate from [the] platen.”  The Federal Circuit also rejected Dr. Chudik’s argument that the prior art reference was not configured for long-lasting fixation because screws and cements used to achieve long-lasting fixation recited in his claim would change the structure of the prior art reference such that it would not achieve the sliding contact the prior art reference allegedly requires.  According to the court, Dr. Chudik pointed to no evidence that the prior art reference was incapable of long-lasting fixation and the prior art’s alleged discussion of sliding contact was irrelevant to whether it was capable of long-lasting fixation.  Finally, the Federal Circuit rejected Dr. Chudik’s argument that the prior art reference did not disclose the “humeral implant” limitation of his application claim because the prior art concerns a glenoid implant: “The patentability of an apparatus claim ‘depends on the claimed structure, not on the use or purpose of that structure.’”

The court’s decision is not precedential, but nevertheless reminds patent practitioners to use care when drafting claims.  Although both negative limitations and functional limitations can serve a purpose, in this case, more tailored claim language may have assisted Dr. Chudik in overcoming the Patent Office’s rejection.  For example, Dr. Chudik argued that using screws and cements to achieve long-lasting fixation in the prior art device would undesirably result in a joint with a limited range of motion. The Federal Circuit countered that his application claim contained no limitation regarding range of motion.  A limitation specifying the range of motion might have improved his patentability position, and more so than the “configured for” functional phrase.  Similarly, Dr. Chudik argued that outwardly-jutting platen portion in the prior art reference was a stem because it “extended away from the main body of platen.”  His application claim did not, however, recite the humeral implant as having, for example, a smooth non-articular surface.  Dr. Chudik’s application was one in a series of divisional applications so the claim strategy may have made sense in that context.  However, patent practitioners who do not anticipate filing more than one application directed to a particular invention should remember to back up broad independent claims with detailed dependent claims in order to have a fallback position if prior art unbeknownst to the inventor is cited against the independent claims.