Conditional Limitations in a System Claim?

Conditional limitations are still limitations, but unfortunately sometimes the USPTO determines that they do not count as limitations at all. As discussed previously (here), in re Schulhauser sets out a way for examiners and the PTAB to ignore limitations as being merely “conditional” and thus not limitations that must be shown in the cited art.

Whether or not the logic of this theory holds, as a practical matter its main effect is to enable easy affirmances at the PTAB. In most instances, however, the detriments of this rule can be overcome with appropriate claim drafting. That must be so, since many inventions rely on making actions conditional on specific parameters. If it were not possible to properly draft claims to avoid the Schulhauser conditional claim issue, then a whole category of technological inventions would never be patentable.

Schulhauser was about a method claim, where the claim terms included certain actions responsive to certain conditions written generally as “performing action Y, if condition X is satisfied.” Some commentators have suggested that system claims would not be subject to conditional claim arguments because they might require, for example, instructions stored in memory that encode the conditions and actions, and so are not optional even if the condition never occurs.

A recent PTAB decision expressly considers conditional claim limitations in a system claim and finds them no different than in a method claim (SN 14/231,802). One potential point here is that the claims at issue in this case did not specify instructions stored in memory, but rather were written in the more functional approach with “configured to.” Claim 1 from the PTAB decision is listed below (emphasis in original).


The PTAB noted that they discerned no distinction between “if” and “when” and thus determined that under the Broadest Reasonable Interpretation, the claims encompass a power conversion system where the controller is not inactive. From this, the PTAB determined:

First, these are not method steps. That seems clear from claim 1. Second, there still must be a controller configured to perform the various functions (even if there is no limitations of structure, such as memory with instructions to perform certain actions responsive to certain conditions). Conditional functions should not negate the controller itself. Third, based on my quick review, the issue of conditional limitations was not raised by the Examiner or the Applicant. The issue only was raised in the PTAB decision, where the PTAB had to effectively admit that the cited art did not teach the claimed controller limitations. The PTAB also did not designate the decision as having any new grounds of rejection. Ouch. Unfortunately, the PTAB’s decision does not address any of these issues.

Nevertheless, such is life and if you are headed to appeal where the art is clearly missing limitations from your method or system that might be categorized as “conditional,” it might make sense to amend the claims to avoid the results noted here. There are various drafting approaches that might be used, one of which is, in a method claim at least, requiring the condition to occur.