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IP Alert: PTAB Provides Guidance on Conditional Claim Language

January 8, 2018

In October 2016, the Patent Trial and Appeal Board (PTAB) took the rare step of declaring its April 2016 decision in Ex parte Schulhauser precedential, the first ex parte appeal designated as such since 2013. In this decision, the PTAB provided clarification on how to interpret and differentiate the patentable weights of conditional language in method claims and system claims, respectively. The particular facts of this case and its treatment by the PTAB set the case apart, and it has since been cited in over 110 ex parte PTAB decisions.

Claim 1 of the Schulhauser application was deemed representative by the PTAB:

1. A method for monitoring of cardiac conditions incorporating an implantable medical device in a subject, the method comprising the steps of:

        collecting physiological data associated with the subject from the implantable device at preset time intervals, wherein the collected data includes real-time electrocardiac signal data, heart sound data, activity level data and tissue perfusion data;

        comparing the electrocardiac signal data with a threshold electrocardiac criteria for indicating a strong likelihood of a cardiac event;

        triggering an alarm state if the electro cardiac signal data is not within the threshold electrocardiac criteria;

        determining the current activity level of the subject from the activity level data if the electrocardiac signal data is within the threshold electrocardiac criteria;

        determining whether the current activity level is below a threshold activity level;

        comparing the tissue perfusion data with a threshold tissue perfusion criteria for indicating a strong likelihood of a cardiac event if the current activity level is determined to be below a threshold activity level;

        triggering an alarm state if the threshold tissue perfusion data is not within the threshold tissue perfusion criteria; and

        triggering an alarm state if the threshold tissue perfusion data is within the threshold tissue perfusion criteria and the heart sound data indicates that S3 and S4 heart sounds are detected,

        wherein if an alarm state is not triggered, the physiological data associated with the subject is collected at the expiration of the preset time interval.

The question of particular interest to the PTAB and in the following discussion is whether the elements of “triggering an alarm state if the electrocardiac signal data is not within the threshold electrocardiac criteria” and “determining the current activity level of the subject from the activity level data if the electrocardiac signal data is within the threshold electrocardiac criteria” should both be given patentable weight for purposes of applying the broadest reasonable interpretation standard under Phillips v. AWH Corp., 415 F.3d 1303, 1316 (Fed. Cir. 2005).

The examiner cited U.S. Patent Publication 2007/0150014 (Kramer) in rejecting claim 1, stating that Kramer discloses the method for monitoring cardiac conditions of claim 1, except that "Kramer . . . does not disclose monitoring tissue perfusion, and does not explicitly state triggering an alarm when signal data indicates a strong likelihood of [a] cardiac event." The examiner cited two other references as teaching these two missing aspects of claim 1.

Appellants contended that the combined teachings of Kramer and the two other references do not disclose "comparing the tissue perfusion data with a threshold tissue perfusion criteria for indicating a strong likelihood of a cardiac event if the current activity level is determined to be below a threshold activity level," as recited in claim 1. Appellants also contended that “the combination of references fails to disclose ’the particular order and conditions imposed on the various comparing, determining and triggering steps by the limitations of independent claim 1.’"

The PTAB, in analyzing claim 1, reasoned that “[d]ue to the language in the ‘triggering’ and ‘determining’ steps, logically, the ‘triggering’ and ‘determining’ steps do not need to be performed, after the ‘comparing’ step if the condition precedent recited in each step is not met. More specifically, the ‘triggering’ and ‘determining’ steps of this claim are mutually exclusive.”

“In other words,” the PTAB reasoned, “claim 1 as written covers at least two methods, one in which the prerequisite condition for the triggering step is met and one in which the prerequisite condition for the determining step is met.”

However, the “determining” step and the steps that follow it are each dependent in some way on the prerequisite conditions in the “determining” step. For example, “the current activity level” (the product of the “determining” step) is utilized in the next two steps and “tissue perfusion data” is introduced in the second of these next two steps (the “comparing” step) and utilized in the final two steps of the method. As such, the PTAB reasoned, when circumstances are such that the “determining” step is not performed, the last five steps of the method are not performed, and are therefore not given patentable weight in the second of the “two methods” identified by the PTAB.

“Thus,” the PTAB concluded, “the broadest reasonable interpretation encompasses a method where only the steps of ‘collecting physiological data . . . comparing the electrocardiac signal data with a threshold electrocardiac criteria . . .’ and ‘triggering an alarm state if the electrocardiac signal data is not within the threshold electrocardiac criteria’ are performed.”

As such, the PTAB reasoned that the examiner, having presented prior art showing the “collecting,” “comparing,” and “triggering” steps, had presented a prima facie case of obviousness, and therefore, under the broadest reasonable interpretation standard, did not need to present prior art teaching the remaining steps of the claim. In the absence of a rebuttal to this prima facie case of obviousness, the PTAB upheld the examiner’s rejection.

Similar logic was the basis for the PTAB’s affirmation of the claims dependent on claim 1.

Claim 11, while similar to claim 1, is written as a system claim (as opposed to a method claim like claim 1) in means-plus-function form. As such, the PTAB reasoned:

Although claim 11 recites functions that are substantially similar to the steps recited in the method of claim 1, . . . claim 11 is directed to a system. The broadest reasonable interpretation of a system claim having structure that performs a function, which only needs to occur if a condition precedent is met, still requires structure for performing the function should the condition occur. This interpretation of the system claim differs from the method claim because the structure (i.e., a processor programmed to perform an algorithm for carrying out the recited function should the recited condition be met) is present in the system regardless of whether the condition is met and the function is actually performed.”

As such, the PTAB gave patentable weight to all the “means” recited in claim 11 and concluded that the examiner had failed to show these teachings were all present in a proper combination for performing the recited functions in the recited order in the prior art cited. Thus, the PTAB overturned the examiner’s rejection of claim 11.

In Schulhauser, the PTAB provides important guidance to patent practitioners for drafting conditional method claims and makes clear that similarly structured system claims (including claims in means-plus-function form) will be interpreted under the broadest reasonable interpretation standard as requiring every element of the recited system, regardless of whether such elements are utilized only on a conditional basis.

With regard to conditional method claims, however, the PTAB makes clear in this decision that conditional method claims can be interpreted under the broadest reasonable interpretation standard as reciting two or more separate methods, dependent on the recited conditions, only one of which methods needs to be shown in the prior art to sustain a prima facie case of obviousness. And, in particular, when subsequent steps recite antecedent elements presented in conditional elements, such subsequent steps are considered only as part of the method that ensues when the conditional elements are present (and such subsequent steps can be disregarded when considering another method that ensues when the conditional elements are not present). Thus, practitioners would do well to carefully consider the introduction of antecedent terms in conditional elements (and not in other conditional elements) and the potential impact of such a claim structure on claim scope under the broadest reasonable interpretation standard.

For further information on this case, please contact Fitch Even partner Thomas E. Lebens, author of this alert.


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