During patent prosecution, sometimes an examiner characterizes key differentiating aspects as “merely” a change in size or shape, or mere scaling. While such rejections are often found in mechanical cases, examiner use them in all sorts of areas, including methods, fabrication, and even machine learning. These rejections can be frustrating because the examiner often uses the MPEP as support for the rejection without any other substantiating evidence. While this makes rejections easy, quick, and efficient for the examiner, it is not always correct.

Focusing today on a change of dimensions, MPEP §§ 2144.04.IV.A.¶ 2 states:

In Gardner v.TEC Syst., Inc., 725 F.2d 1338, 220 USPQ 777 (Fed. Cir. 1984), cert. denied, 469 U.S. 830, 225 USPQ 232 (1984), the Federal Circuit held that, where the only difference between the prior art and the claims was a recitation of relative dimensions of the claimed device and a device having the claimed relative dimensions would not perform differently than the prior art device, the claimed device was not patentably distinct from the prior art device.

Examiners can take this to extremes - any change in relative size, for some, is something that no longer needs to be found in the prior art because it is, allegedly, per se obvious. However, it must first be stressed that this rule applies only when there is just a change in relative dimensions. So, changing from a circular shape to a square shape would not be merely a change in relative dimension. In other words, applicants should push back if an examiner argues, for example, that a square was merely a different relative dimension from a circle when one compares each point on the perimeter one at a time - on the theory that the rule is just applied repeatedly (and yes, an examiner did make that argument in a real case).

Additionally, a change in function negates a finding of obviousness under this test. A recent example that illustrates a rejection relying on MPEP 2144.04 relates to filter assemblies for use with chromatographic columns - Appeal 2021-000835, Application 14/896,135 in TC 1700. Claim 1 relates to a press-fit configuration:

1. A filter comprising:
a porous element including an outer surface having a side wall,
a compression element having an inner surface surrounding the outer surface of the porous element and having an outer surface, the inner surface configured to receive the porous element in a slip-fit relationship, thereby forming an assembly, and
a housing having an opening formed therein, the opening configured to receive and retain the assembly in a press-fit relationship, wherein when the opening receives the assembly in the press-fit relationship, a first force applied to the outer surface of the compression element is converted into a second force between the inner surface of the compression element and the outer surface of the porous element, so that the second force is sufficient to retain the porous element within the compression element.

The rejection relied on a combination of references (Doehren and Brownlee). However, even then, there was no teaching of the claimed press-fit relationship. But that was no problem for this examiner, as they alleged one can merely change the dimension of various components so as to create a press-fit relationship. Thus, according to the examiner, following MPEP 2144.04.IV.A means that the claims are obvious.

In other words, everyone agreed that Doehren was silent regarding “a first force applied to the outer surface of the compression element is converted into a second force between the inner surface of the compression element and the outer surface of the porous element, so that the second force is sufficient to retain the porous element within the compression element.” Nevertheless, the examiner reasoned that the only difference between claim 1 and Doehren’s disclosure was “a recitation of relative dimensions of the inner circumference of the opening [in the housing] and the outer circumference of the assembly.” From there, the examiner’s work was done in maintaining the rejection because, with a few minor adjustments of relative dimensions, the prior art was fully capable of applying a first force to the outer surface of the compression element which is converted into a second force between the inner surface of the compression element and the outer surface of the porous element. The examiner cited MPEP § 2114.II for good measure, because any claimed function does not differentiate structure.

There are numerous problems with the examiner’s approach. Breaking down the examiner’s logic, one can see the bootstrapping — relative dimensions are not a patentable distinction unless they provide a new function, but function is irrelevant to a structural claim. The Office does not address how this logic seems to rewrite the case law of Gardner. Further, the question is not whether the prior art can provide the new function once it is modified, but rather whether a new function is obtained through the modification of relative dimensions.

As the PTAB points out in their decision,

That in Gardner the Federal Circuit upheld the trial court’s determination that the dimensional limitations (e.g., “spaced therefrom as closely as is mechanically practicable,”) were “limitation[s] without a function,” and “the dimensional limitations did not specify a device which performed and operated any differently from the prior art.” Gardner, 725 F.2d at 1340, 1346, 1349. The facts in the instant case are distinguishable. As elaborated infra, a difference in the relative dimensions of the claimed housing and compression element would result in a difference in performance from that of Doehren

So, make sure to identify when an examiner is stretching the MPEP rules (and relevant case law) beyond it’s appropriate scope. And when drafting applications, explain the function achieved by the relationship of elements so that when needed there is evidence of new functions.