The Patent Office sometimes takes a piecemeal approach to analyzing claim limitations as a way to obtain a(n) (unreasonably) broad interpretation, which of course makes sustaining a rejection easier. In Wonderland, like in re Smith, the Federal Circuit is rightly having none of it.
Wonderland deals with a baby crib that has
The PTAB interpreted the "fabric member" as being "one or more fabric pieces" and the "enclosure member" as being one or more members. On its face, this seems perfectly correct. Of course a claim with "an" element could mean that there are more than one such element. But of course, the claim did not only require the elements in isolation. The PTAB was in essence trying to pull a fast one by bootstrapping their interpretation so as to encompass the cited art.
The PTAB actually used a two-step bootstrap. First, the PTAB interpreted the fabric member to be one or more members. Then, since the prior art shows multiple fabric members that together defined a surround wall around the bed frame, the PTAB was able to say the prior art showed the claim element. But, the logical problem with the PTAB's analysis is that their approach effectively read out limitations in the claim. Namely, the claim, through the rules of antecedent basis, expressly states that the fabric member (singular) defines the surrounding wall. Thus, whether or not there are additional fabric members, that does not mean that the claim would encompass a situation where multiple fabric members are required to define the surrounding wall. So, by separating the claim elements and analyzing them in isolation, the PTAB erroneously ignored an actual claim element.
The Federal Circuit criticized the PTAB for this approach and explained that the ordinary language of the claims indicates that a single fabric or enclosure member must be capable of separating the interior of the claimed crib from the exterior. "Claim 1 requires the fabric member 'define a surrounding wall' and 'delimit an enclosed space.'"
While this was a simple situation, Examiners and the PTAB often use this tactic and it can be buried deep in the analysis and so is often difficult for applicants to spot and attack. Thus, make sure to be clear on the linking of elements in the claims and do not let the USPTO pull a fast one on you like they tried in Wonderland (and Smith).