What is the KSR v. Teleflex standard for obviousness?
KSR International Co. v. Teleflex Inc. is the 2007 Supreme Court decision that remains the controlling standard for patent obviousness in U.S. patent law. Understanding it is central to prosecution strategy: examiners draw on it every time they combine references to reject a claim under 35 U.S.C. § 103.
The statutory hook: 35 U.S.C. § 103
Obviousness is a statutory bar. Under 35 U.S.C. § 103, a patent may not be obtained if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date to a person having ordinary skill in the art.
The Graham framework (unchanged by KSR)
KSR reaffirmed, not replaced, the foundational four-factor test from Graham v. John Deere Co. (1966). Graham established four underlying factual inquiries: the scope and content of the prior art; differences between the prior art and the claims at issue; the level of ordinary skill in the pertinent art; and secondary considerations such as commercial success, long-felt need, and failure of others. These four factors remain the obligatory structure of every obviousness analysis. KSR builds on top of them.
What KSR changed: a flexible approach to TSM
Before KSR, the Federal Circuit applied the TSM (teaching-suggestion-motivation) test to require that an examiner identify an explicit teaching, suggestion, or motivation in the prior art before combining references against a claim. KSR held that this rigid application was inconsistent with the Graham framework's expansive and flexible approach, and that the analysis cannot be confined by a formalistic conception that limits the inquiry.
KSR did not eliminate TSM. It retained TSM as one legitimate basis for combining references, now codified as rationale G in MPEP § 2143, while rejecting any rule that requires explicit TSM evidence as the sole permissible path to obviousness. The Court also recognized that motivation to combine can arise from sources beyond explicit patent disclosures: in many fields market demand, rather than scientific literature, drives design trends.
The predictability principle
KSR's most-cited holding is that a combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results. If the combination produces what a skilled artisan would have expected, there is no genuine inventive contribution. The practical consequence is that a combination producing unexpected or superior results is far harder for an examiner to sustain.
POSITA as a person of ordinary creativity
KSR characterized the person of ordinary skill in the art (POSITA) not as a mechanical executor but as a person of ordinary creativity, not an automaton, who can apply inferences and creative steps to fit the teachings of multiple references together like pieces of a puzzle. An examiner therefore does not need a reference that explicitly instructs combining the other references. The creativity and common sense that a skilled artisan brings to the field can supply the motivation.
The "obvious to try" doctrine
KSR restored the "obvious to try" theory that some Federal Circuit decisions had narrowed. When there is a known problem and a finite number of identified, predictable solutions, pursuing those options represents ordinary skill rather than innovation and qualifies as obvious under § 103.
The critical qualifiers are finite and predictable. If the solution space is large, the results are uncertain, or choosing among candidates requires inventive judgment, the obvious-to-try rationale does not apply.
The seven KSR rationales (MPEP § 2143)
The USPTO distilled KSR into seven rationales that examiners cite when combining references. Every § 103 rejection grounded in KSR will rely on one or more of these:
| Rationale | What it says |
|---|---|
| A | Combining familiar prior art elements by known methods yields predictable results |
| B | Simple substitution of one known element for another produces predictable results |
| C | Applying a known technique to improve similar devices in the same way |
| D | Applying a known technique to a prior art device ready for improvement, with predictable results |
| E | Obvious to try: selecting from a finite number of identified, predictable solutions with reasonable expectation of success |
| F | Adapting known work based on design incentives or market forces, yielding predictable variations in the same or a different field |
| G | Teaching, suggestion, or motivation in the prior art to modify or combine references |
Secondary considerations: rebutting a KSR rejection
Secondary considerations (objective indicia of nonobviousness) such as commercial success, long-felt but unsolved need, failure of others, unexpected results, and copying must have a legally sufficient nexus to the claimed invention to carry weight against a prima facie case of obviousness. They must be considered as part of the whole obviousness analysis whenever they are properly presented; they are not an afterthought.
Secondary consideration evidence is typically submitted through a declaration under 37 C.F.R. § 1.132 from a company official or technical expert, supported by comparative data and specific facts. Establishing nexus means showing that the commercial success or other objective indicia flows from the claimed features of the invention, not from unrelated factors such as marketing spend or an exclusive license.
Practical notes for practitioners
- Target the predictability weakness. The most effective argument against a rationale-A or rationale-B rejection is to show that the combination does not yield predictable results. Comparative test data showing unexpected or superior properties is the sharpest rebuttal tool you have.
- Test the finite-solutions question for rationale E. If the solution space was large or the results were unpredictable at the time of filing, obvious-to-try fails. Establishing that fact requires evidence, not attorney argument alone.
- Submit secondary-consideration evidence early. Secondary considerations are part of the full analysis from the beginning. File a 1.132 declaration as soon as you have hard data: comparative results, documented industry surprise, or evidence that the field had tried and failed. Late-stage submissions can be discounted.
- Frame responses to the stated rationale. Examiners will identify one or more of the seven rationales when combining references. Addressing the specific rationale relied on, rather than arguing generally that the combination is improper, is more persuasive and builds a cleaner prosecution history if the case reaches litigation.
- Watch common-sense citations. Post-KSR, examiners sometimes invoke "common sense" as a substitute for a specific reference. When an examiner relies on common sense as a rationale for combining references or supplying a missing claim limitation, the USPTO's examination guidelines require that the common sense be supported by evidence and a reasoned explanation. Challenge unsupported common-sense assertions directly.