Patents

KSR v. Teleflex: The Day the Rigid Obviousness Test Died

The Supreme Court replaced the Federal Circuit's mechanical teaching-suggestion-motivation test with a flexible, common-sense obviousness inquiry that still governs every Section 103 dispute today.

February 10, 2025
An adjustable automobile accelerator pedal with an electronic position sensor
The patent in suit combined an adjustable gas pedal with an electronic throttle sensor. Shutterstock
Educational content, not legal advice. This article explains general legal concepts. It does not create an attorney–client relationship. For your specific situation, consult a licensed attorney.

KSR International Co. v. Teleflex Inc., No. 04-1350, 550 U.S. 398 (Apr. 30, 2007), is the case every later obviousness opinion either applies or distinguishes. In a unanimous opinion authored by Justice Kennedy, the Supreme Court reversed the Federal Circuit and reinstated a district court’s summary judgment that claim 4 of U.S. Patent No. 6,237,565 was invalid as obvious under 35 U.S.C. § 103. More importantly, the Court used the occasion to dismantle the rigid version of the “teaching, suggestion, or motivation” (TSM) test the Federal Circuit had been applying and to restore the flexible, fact-driven framework of Graham v. John Deere Co. Nearly two decades later, KSR remains the gravitational center of obviousness law.

At a glance

  • Case: KSR Int’l Co. v. Teleflex Inc., No. 04-1350 (U.S. Apr. 30, 2007).
  • Court: Supreme Court of the United States; opinion by Justice Kennedy for a unanimous Court.
  • Patent: U.S. Patent No. 6,237,565 (the “Engelgau” patent), claim 4, directed to an adjustable vehicle control pedal combined with an electronic throttle-position sensor.
  • Posture: Review of a Federal Circuit decision that had reversed a district court grant of summary judgment of invalidity.
  • Holding: The Federal Circuit applied the TSM test too rigidly; the claim was obvious as a matter of law; summary judgment of invalidity reinstated.
  • Doctrinal core: Obviousness is an “expansive and flexible” inquiry. Combining familiar elements by known methods is likely obvious when it yields no more than predictable results, and the analysis may rest on common sense, design incentives, and market forces — not only on an explicit prior-art suggestion.

The technology and the litigation path

The dispute was about a humble component: the gas pedal. Modern vehicles use electronic throttle controls, in which a sensor reads pedal position and signals the engine, rather than a mechanical cable. Separately, adjustable pedals let a driver move the pedal closer or farther to suit their height. The Engelgau patent claimed a pedal assembly that mounted an electronic sensor on a fixed pivot point of an adjustable pedal so that the sensor’s output stayed accurate regardless of pedal adjustment.

KSR, a parts supplier, added a modular sensor to an existing adjustable pedal it already made for General Motors. Teleflex sued for infringement. The district court, working through the Graham factors, found a host of prior-art references disclosing adjustable pedals, electronic sensors, and the advantages of mounting a sensor on a fixed pivot. It granted KSR summary judgment of invalidity. The Federal Circuit reversed, holding the district court had not been rigorous enough in identifying a specific teaching, suggestion, or motivation that would have led a skilled artisan to combine the references in the claimed way.

What the Court actually rejected

It is a common misreading to say KSR abolished the motivation requirement. It did not. The Court was careful to say that “there is no necessary inconsistency between the idea underlying the TSM test and the Graham analysis,” and that a flexible TSM inquiry “captured a helpful insight.” A reason to combine references is still needed, because a fact-finder must guard against the seductive logic of hindsight — the temptation to treat an invention as obvious merely because, once disclosed, it looks simple.

What the Court rejected was the rigid, mandatory formalism the Federal Circuit had layered onto TSM: the demands that the motivation appear in the prior art itself, that it address the same problem the patentee confronted, and that the patentee’s particular purpose control the analysis. Those preconditions, the Court said, were “narrow” and “rigid” rules that constrained the inquiry in ways § 103 and Graham never authorized. The error was to make a useful heuristic into a “rigid and mandatory” rule that excluded other legitimate sources of motivation.

In their place, the Court restored breadth. A motivation to combine “need not be the same” as the patentee’s. It can arise from the nature of the problem, from design incentives, from market demand, or from the simple fact that there are a finite number of predictable solutions a skilled artisan would try. Crucially, the Court announced that “a person of ordinary skill is also a person of ordinary creativity, not an automaton.” That single sentence reoriented the entire field: the hypothetical skilled artisan can connect dots, draw inferences, and apply common sense.

Predictable results, obvious to try, and the danger of hindsight

Two doctrines that KSR either created or revived now appear in nearly every obviousness brief.

First, the predictable-results principle: “The combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results.” Where each element performs the same function in combination that it performed separately, and the combination is within the technical grasp of a skilled artisan, the claim is vulnerable. The Engelgau claim fit this mold precisely — an adjustable pedal that did what adjustable pedals do, plus a sensor that did what sensors do, mounted where a person of skill would expect to mount it.

Second, obvious to try: the Court rejected the Federal Circuit’s prior rule that “obvious to try” could never establish obviousness. When there is a design need or market pressure to solve a problem and a finite number of identified, predictable solutions, a skilled artisan has good reason to pursue the known options within her grasp. If that pursuit leads to the anticipated success, “it is likely the product not of innovation but of ordinary skill and common sense.” This is the doctrine that, in the pharmaceutical and chemical arts, has since generated a vast body of “lead compound” and “result-effective variable” case law.

The Court paired this loosened standard with an explicit warning. Fact-finders must be “cautious of arguments reliant upon ex post reasoning,” because the very ease of describing a combination after the fact is what makes hindsight so dangerous. The discipline KSR demands, then, is not the absence of common sense but the articulation of it: a tribunal must explain the reasoning, with “some rational underpinning,” rather than declaring a result inevitable.

Open questions

  • How much articulation is enough? KSR requires “some rational underpinning” for a combination but did not specify how detailed the explanation must be. Later cases — including the Federal Circuit’s repeated insistence that a motivation be stated and supported — wrestle with the line between permissible common sense and impermissible conclusory assertion.
  • When does “common sense” need evidence? The Court invoked common sense freely. Subsequent Federal Circuit decisions have cautioned that common sense generally cannot supply a missing claim limitation and usually must be supported by reasoned analysis or record evidence, not invoked as a bare conclusion.
  • How do objective indicia fit a flexible standard? KSR reaffirmed that secondary considerations remain part of the Graham inquiry, but the opinion said comparatively little about how a flexible obviousness analysis should weigh commercial success, long-felt need, and failure of others — a question later cases such as In re Cyclobenzaprine addressed head-on.

Implications

  • For patent challengers: KSR is a gift, but a disciplined one. The flexible standard permits common-sense combinations, yet the challenger still must articulate a reason to combine with a rational underpinning. Element-matching alone does not win.
  • For patent owners: Predictable combinations of known parts are exposed. The strongest defense is evidence that the combination produced unexpected results, that the art taught away, or that objective indicia show nonobviousness.
  • For patent prosecutors: Claims reciting familiar elements performing familiar functions invite a predictable-results rejection. Build the specification to support unexpected results and synergy that go beyond the sum of the parts.
  • For litigators and the PTAB: The lodestar is reasoned explanation. A flexible inquiry is not a license for conclusory findings; tribunals must show the rational underpinning for every combination.

Frequently asked questions

Did KSR eliminate the motivation-to-combine requirement? No. It expanded the permissible sources of motivation — problem, design need, market pressure, common sense — and rejected the rule that the motivation must appear in the prior art and match the patentee’s purpose. A reason to combine is still required to guard against hindsight.

What is the single most quoted line from KSR? Likely “a person of ordinary skill is also a person of ordinary creativity, not an automaton,” closely followed by the predictable-results formulation. Both appear constantly in modern obviousness briefing.

How did KSR change “obvious to try”? It rejected the Federal Circuit’s categorical rule that obvious-to-try could never show obviousness. Where there is a finite number of identified, predictable solutions and a reason to pursue them, arriving at one may be ordinary skill rather than invention.

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