Imagine That IP Law Blog

Determining whether a claimed invention is obvious under 35 U.S.C. § 103 often depends on whether the prior art provides a clear motivation for modifying existing knowledge. Central to this analysis is the concept of a “result-effective variable”—a parameter recognized in the prior art as influencing a particular property or outcome. If a variable is deemed result-effective, it suggests that a person of ordinary skill in the art (POSITA) would have been motivated to adjust or optimize that parameter in pursuit of improved results. However, if the prior art does not establish that a variable affects the desired result, there is no reason to assume that a POSITA would have been driven to modify it. The recognition, or lack thereof, of a result-effective variable can play a crucial role in establishing a prima facie case of obviousness. Courts have consistently emphasized this principle, making it clear that without evidence of a meaningful relationship between a variable and a desired property, any claim of obviousness is significantly weakened.

What Is a Result-Effective Variable?

In Genentech, Inc. v. Hospira, Inc., the Federal Circuit clarified this principle:

"One way in which the patentee may rebut the presumption of obviousness is by showing ‘that there is something special or critical about the claimed range’... [a]nother way in which the presumption can be rebutted is by showing that a process parameter, such as temperature, was not recognized as ‘result-effective.’" (946 F.3d 1333, 1341 (Fed. Cir. 2020))

In other words, if the claimed variable was not known to affect the desired outcome, then adjusting it—even within a range disclosed by the prior art—may not be obvious.

How Does It Affect a Prima Facie Case of Obviousness?

Establishing a prima facie case of obviousness under 35 U.S.C. § 103 requires more than merely identifying similarities between the claimed invention and prior art—it demands a clear demonstration that a POSITA would have both the capability and the motivation to modify or combine elements from the prior art in a way that leads to the claimed invention. This motivation can be supported by some indication in the prior art that would reasonably prompt a POSITA to make such adjustments. Without this foundational reasoning, an obviousness argument cannot stand.

Central to this analysis is the concept of a result-effective variable, as described above. Identifying a variable as result-effective is essential because it provides the justification for why a POSITA would attempt to adjust or optimize that variable. If the prior art suggests that changing a specific parameter could produce beneficial or predictable results, it creates a motivation for a skilled practitioner to experiment with that parameter. In the absence of such recognition, any assertion that the adjustment would have been obvious lacks the necessary factual and legal support.

The importance of this concept was underscored by the Federal Circuit in Genentech, Inc. v. Hospira, Inc., which explained:

"The idea behind the ‘result-effective variable’ analysis is... that a person of ordinary skill would not always be motivated to optimize a parameter ‘if there is no evidence in the record that the prior art recognized that particular parameter affected the result.’" (946 F.3d 1333, 1341 (Fed. Cir. 2020))

This principle was further reinforced in In re Applied Materials, Inc., where the Federal Circuit emphasized that:

"The absence of any disclosure regarding the relationship between the variable and the affected property may preclude a finding that the variable is result-effective." (692 F.3d 1289, 1297 (Fed. Cir. 2012))

In other words, unless the prior art explicitly acknowledges a connection between adjusting a specific variable and influencing the relevant outcome, there is no valid basis for asserting that a POSITA would have been motivated to make such modifications. Without this recognition, any rationale for adjusting the variable collapses, weakening the case for obviousness.

Conversely, when the prior art does recognize that a particular variable affects a desired result, that variable is classified as result-effective. This concept was reaffirmed in E.I. du Pont de Nemours & Co. v. Synvina C.V., where the court stated:

"Likewise, if the prior art does recognize that the variable affects the relevant property or result, then the variable is result-effective." (904 F.3d 996, 1009 (Fed. Cir. 2018))

This recognition is critical because it establishes a clear basis for arguing that a POSITA would have been motivated to adjust the variable to achieve a beneficial result. In the absence of such evidence— where the prior art fails to suggest any connection between the variable and the desired outcome— an examiner or a court cannot reasonably find that a POSITA would have been motivated to make such changes. Without a recognized link, the argument for obviousness becomes untenable, leaving the claimed invention on stronger legal ground.

Breadth of Prior Art Disclosures: Why It Matters

In cases where prior art discloses overly broad ranges, it becomes harder to argue that the claimed invention was obvious. The Federal Circuit addressed this in Genetics Institute, LLC v. Novartis Vaccines & Diagnostics, Inc.:

"[A] prior art reference does not render a claim obvious when 'the disclosed range is so broad as to encompass a very large number of possible distinct compositions thus requiring nonobvious invention.'" (655 F.3d 1291, 1306 (Fed. Cir. 2011))

This decision distinguished situations where prior art ranges are narrow enough to encourage routine optimization by a POSITA from those where the breadth of the range suggests genuine invention rather than routine experimentation.

When a Variable Is Not Result-Effective

Two pivotal cases provide significant insight into when a variable should not be considered result-effective, demonstrating how the absence of prior art recognition can undermine an obviousness argument.

In In re Antonie, the U.S. Court of Customs and Patent Appeals (C.C.P.A.), the predecessor court to the Federal Circuit, addressed a situation where the claimed invention involved a specific ratio of variables that was neither disclosed nor suggested by the prior art. The court found that the prior art not only failed to disclose the precise ratio claimed in the application, but it also lacked any indication that this ratio was relevant to the desired property or functional result of the invention. Without the recognition that modifying this ratio would lead to any meaningful outcome, there was no motivation for a person of ordinary skill in the art (POSITA) to explore or optimize that parameter. As the court explained:

"[T]he court held that since the prior art did not disclose the claimed ratio, nor even recognize that one of the variables in the ratio was relevant to the desired property, the claims were not rendered obvious." (559 F.2d 618, 618 (C.C.P.A. 1977))

This ruling underscore the critical need for prior art to not only disclose specific parameters but also acknowledge their potential significance in achieving the desired result. Without such acknowledgment, a modification cannot be reasonably considered an obvious improvement.

Similarly, In re Yates further emphasized the necessity of recognizing a variable’s influence on the desired outcome. In that case, the C.C.P.A. rejected an obviousness finding on the grounds that the prior art failed to establish any relationship between the variable at issue and the affected property of the invention. The claimed variable was not identified in the prior art as influencing the outcome, nor was there any supporting evidence indicating that such a relationship was understood by those skilled in the field. The court held:

"[T]he court found a variable not result-effective because there was no teaching of the claimed relationship between the variable and an affected property and there was 'no evidence of this relationship in the prior art.'" (663 F.2d 1054, 1056 (C.C.P.A. 1981))

This decision highlights that, in the absence of clear guidance or acknowledgment in the prior art, there is no reasonable basis to argue that a POSITA would have been motivated to adjust or optimize that variable.

Practical Implications for Patent Practitioners

When responding to an obviousness rejection, it’s essential to challenge a recognized relationship directly by arguing that the prior art does not establish the claimed variable as result-effective. Additionally, highlighting the breadth of prior art disclosures can be vital. If the prior art covers an excessively broad range, the Genetics Institute case can be cited to demonstrate that routine optimization wasn’t apparent. Presenting evidence of unexpected results can further strengthen your position by showing that the claimed invention yields outcomes that could not have been predicted from the prior art. Finally, leveraging relevant case law strategically, including decisions like Genentech, E.I. du Pont de Nemours & Co., In re Antonie, and In re Yates, can reinforce arguments that a prima facie case of obviousness has not been established.

Conclusion

The concept of a result-effective variable can be the linchpin in determining whether a patent claim is obvious. Without clear recognition in the prior art that a specific variable affects the desired result, a prima facie case of obviousness falters. For patent practitioners, understanding and applying this doctrine can be a powerful tool in overcoming § 103 rejections and securing patent protection.