Does an Examiner Need a Reason to Combine Prior Art? What KSR Taught Us About Obviousness
How KSR v. Teleflex Changed the Standard for Combining Prior Art in § 103 Obviousness Rejections
One of the most common obstacles to obtaining a patent is a rejection under 35 U.S.C. § 103, where a patent examiner argues that the claimed invention would have been “obvious” to a person having ordinary skill in the art.
Often, the examiner reaches that conclusion by combining two or more prior-art references.
But that raises an important question:
"What gives an examiner the right to combine those references in the first place?"
The Supreme Court addressed that issue in KSR International Co. v. Teleflex Inc., 550 U.S. 398 (2007), one of the most important modern cases concerning patent obviousness. To understand its answer, we need to start with the rule it replaced.
Before KSR: The TSM Test
Before KSR, the Federal Circuit frequently applied for the Teaching-Suggestion-Motivation, or TSM, test.
Under that approach, courts looked for some teaching, suggestion, or motivation that would have led a person of ordinary skill in the art to combine existing references. The purpose was to prevent hindsight.
Once an invention exists, it can be easy to look backward, find each claimed element scattered across the prior art, and conclude that the combination must have been obvious. But the fact that every individual component was known does not necessarily mean that the claimed combination was obvious.
The TSM test required some reason, independent of the inventor’s own disclosure, showing why a skilled person would have combined the references. That reason could come from the prior art itself, the nature of the problem being solved, or the knowledge of a person having ordinary skill in art.
The Federal Circuit applied for the test strictly. Broad or conclusory statements were not enough. The motivation to combine had to be supported by evidence.
KSR agreed that hindsight remains a real concern, emphasizing that a patent is not proved obvious merely because each individual element was already known.
Why the TSM Test Became a Problem
The facts of KSR show how this worked in practice. Teleflex’s patent claimed an adjustable gas pedal with an electronic sensor mounted on a fixed pivot point.
Neither feature was new. The Asano patent already disclosed an adjustable pedal with a fixed pivot point, and the Smith patent taught that the sensor belongs on a fixed part of the pedal assembly. Combining the two produces essentially the claimed pedal.
Even so, the Federal Circuit upheld the claim. It reasoned that Asano could not supply motivation to combine because Asano was designed to solve a different problem. It also held that showing the combination was “obvious to try” proved nothing. See KSR, 550 U.S. 398.
What Did the Supreme Court Decide?
In KSR International Co. v. Teleflex Inc., 550 U.S. 398 (2007), the Supreme Court held that the Federal Circuit had applied the TSM test too rigidly.
The Court did not reject teaching, suggestion, or motivation as relevant. Instead, it explained that obviousness must be evaluated more flexibly.
A reason to combine prior art does not need to appear as an express statement in a patent or publication. It may also arise from market demands, known problems, design incentives, predictable solutions, or the ordinary creativity of a person skilled in art.
The Court also recognized that “obvious to try” reasoning may support an obviousness conclusion where there are a finite number of identified predictable solutions.
At the same time, the Court did not give examiners unlimited discretion. Hindsight remains a concern, and an obviousness of determination still requires a reasoned basis for combining prior art.
In short, KSR did not eliminate TSM reasoning. It rejected treating TSM as the only permissible route to a finding of obviousness.
So, Is the TSM Test Mandatory Today?
An examiner does not have to find a sentence in the prior art saying, in effect, “combine Reference A with Reference B.”
But KSR did not let examiners combine references however they wished.
An obviousness rejection still requires a reasoned explanation for why a person of ordinary skill in the art would have modified or combined the prior art in the manner claimed.
The examiner must still identify “an apparent reason to combine the known elements in the fashion claimed by the patent at issue.”
That reason can come from the teachings of several patents, from demands in the marketplace, or from the background knowledge of a person of ordinary skill.
And “this analysis should be made explicit.”
The Court adopted the rule of In re Kahn, 441 F.3d 977, 988 (Fed. Cir. 2006): “rejections on obviousness grounds cannot be sustained by mere conclusory statements; instead, there must be some articulated reasoning with some rational underpinning to support the legal conclusion of obviousness.”
That principle remains reflected in USPTO examination practice today.
USPTO practice follows this. Every rationale an examiner relies on, including the TSM rationale, requires specific findings, such as a finding of a reasonable expectation of success.
What Did KSR Teach Us About Responding to § 103 Rejections?
KSR changed the question applicants should ask when reviewing an obviousness of rejection.
Instead of asking only:
“Where is the explicit teaching, suggestion, or motivation to combine these references?”
the better question is:
“Has the examiner actually provided a persuasive, factually supported reason why a person of ordinary skill would have made this particular combination?”
A proper § 103 analysis requires more than showing that each claim element appears somewhere in the prior art. The examiner must also explain why those teachings would have been combined or modified in the claimed manner.
That explanation should then be tested.
Would the proposed combination actually produce the claimed invention?
Would it change how a reference works or defeat its intended purpose?
Was the result predictable? Was there a reasonable expectation of success?
Is the rationale supported by evidence, or is it merely a conclusion?
The key issue is not whether the prior art contains an express instruction to combine the references. It is whether the record provides a legally sufficient reason for the proposed combination.
The Takeaway
KSR made the analysis of whether an invention would have been considered obvious more flexible, but it did not mean that every combination of known elements is automatically unpatentable.
The TSM test is no longer a mandatory, rigid test. An examiner does not necessarily need an explicit teaching in the prior art telling someone to combine two references.
But the examiner still needs an explicit, reasoned explanation, supported by the record, for why the claimed invention would have been obvious.
For patent practitioners, that means the strongest response to a § 103 rejection is often
not simply:
“There is no explicit teaching to combine these references.”
The better question is:
“Why would a person of ordinary skill in the art have actually made this combination, in this manner, to arrive at the claimed invention?”
Conclusion
KSR did not eliminate the need for a reason to combine prior art. Instead, it made the obviousness analysis more flexible by rejecting a rigid requirement that the reason must appear as an explicit teaching, suggestion, or motivation in the prior art.
For patent applicants, the key question is whether the examiner has provided a clear, factually supported explanation showing why a person of ordinary skill in the art would have combined or modified the cited references in the claimed manner.
A strong response to a § 103 rejection should therefore focus not only on whether the claimed elements are present in the prior art, but also on whether the examiner's rationale for combining those references is legally and factually sufficient.
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If you have received a § 103 obviousness rejection or have questions about a patent application, prior art, or USPTO examination strategy, Rotek Law can review the Office Action and help assess the available options for responding.
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About the Author
Cristian A. Rodriguez, Esq. is a registered U.S. patent attorney and the founder of Rotek Law, an intellectual property law firm representing inventors, entrepreneurs, and businesses in patent, trademark, copyright, and other intellectual property matters.
Disclaimer
This article is provided for general informational and educational purposes only and does not constitute legal advice. Patentability, obviousness, and the appropriate response to a USPTO rejection depend on the specific facts, claims, prior art, and procedural history of each application. Reading this article or contacting Rotek Law does not create an attorney-client relationship. Readers should consult a qualified attorney regarding their specific circumstances.
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