Swinehart invoked in Ex parte Wedemeyer
A patent applicant is free to recite features of an apparatus either structurally or functionally. See In re Swinehart, 439 F.2d 210, 212 (CCPA 1971) (“[T]here is nothing intrinsically wrong with [defining something by what it does rather than what it is] in drafting patent claims.”). As such, a § 112 rejection of an apparatus claim solely on the basis that the claim fails to set forth any additional structure is improper.
Where the Patent Office has reason to believe that a functional limitation is an inherent characteristic of the prior art, it can require an applicant to show that the prior art does not possess the claimed functional features. In re Schreiber, 128 F.3d 1473, 1478 (Fed. Cir. 1997) (citing Swinehart, 439 F.2d at 213) (once the PTO made a showing that the prior art disclosed the claimed functional feature, the burden shifted to the applicant to show that the prior art structure did not inherently possess the functionally defined limitations of his claimed apparatus).