Obviousness under § 103

Obviousness is the most frequently litigated invalidity doctrine in patent law. A claim is invalid if its differences from the prior art would have been obvious to a person of ordinary skill in the art at the time the invention was made. The framework is fact-intensive, the standard is flexible, and the doctrine functions as the principal check on the issuance of patents that combine known elements in predictable ways.

The rule

A patent claim is invalid for obviousness 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 of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains." 35 U.S.C. § 103. The inquiry is one of law, decided on underlying findings of fact organized by the four Graham factors.

The Supreme Court reaffirmed and refined this analysis in KSR International Co. v. Teleflex Inc., 550 U.S. 398 (2007), which rejected a rigid application of the Federal Circuit's teaching-suggestion-motivation (TSM) test in favor of an "expansive and flexible approach." After KSR, the inquiry asks whether the claimed combination would have been obvious to a person of ordinary skill, drawing on common sense, design needs, market forces, and the predictable use of known elements according to their established functions.

Statutory and constitutional source

Congress codified the obviousness requirement in the 1952 Patent Act. 35 U.S.C. § 103. The Leahy-Smith America Invents Act amended § 103 to align it with the AIA's first-inventor-to-file regime, replacing the "at the time the invention was made" reference point with "before the effective filing date of the claimed invention." The amended language applies to patents and applications having an effective filing date on or after March 16, 2013; pre-AIA § 103 governs earlier patents.

The constitutional anchor is the same Article I, Section 8, Clause 8 that grounds the rest of patent law. The Supreme Court has long read that clause as imposing a substantive nonobviousness requirement, beginning with Hotchkiss v. Greenwood, 52 U.S. (11 How.) 248 (1850), and culminating in Graham's declaration that § 103 was a codification of the constitutional standard.

The framework the courts apply

The Graham factors

Graham v. John Deere Co., 383 U.S. 1 (1966), set out the framework that still governs. A court must determine:

1. The scope and content of the prior art;
2. The differences between the prior art and the claims at issue;
3. The level of ordinary skill in the pertinent art; and
4. Any objective indicia of nonobviousness — also called secondary considerations.

These factual inquiries support the ultimate legal conclusion of obviousness or nonobviousness. Each must be made; failure to address any factor — particularly secondary considerations when raised — is reversible error.

Level of ordinary skill

The level of ordinary skill is itself a factual finding. Federal Circuit decisions identify factors including the educational level of the inventor, the type of problems encountered in the art, prior-art solutions, the rapidity with which innovations are made, the sophistication of the technology, and the educational level of active workers in the field. Environmental Designs, Ltd. v. Union Oil Co. of California, 713 F.2d 693 (Fed. Cir. 1983). The level of skill informs both what the prior art teaches and how it would have been combined.

Combination of references and motivation to combine

Unlike anticipation, obviousness permits combinations of multiple references. The principal question is whether a person of ordinary skill would have been motivated to combine the references and would have had a reasonable expectation of success. After KSR, motivation may come from the references themselves, from the nature of the problem, from the knowledge and creativity of the skilled artisan, from market forces, or from common sense. The Federal Circuit has nonetheless required that obviousness rationales be supported by evidence; conclusory assertions of common sense are insufficient. In re Van Os, 844 F.3d 1359 (Fed. Cir. 2017); Arendi S.A.R.L. v. Apple Inc., 832 F.3d 1355 (Fed. Cir. 2016).

The post-KSR rejection of rigid TSM

Before KSR, the Federal Circuit applied the teaching-suggestion-motivation test as a near-mandatory requirement that obviousness must rest on a teaching, suggestion, or motivation in the prior art to combine. The Supreme Court in KSR held that "rigid preventative rules that deny factfinders recourse to common sense" are inconsistent with § 103. KSR, 550 U.S. at 421. The Court approved the use of TSM as one helpful insight but rejected its elevation to a mandatory formal test. The Court also approved use of "obvious to try" reasoning where a finite number of identified, predictable solutions exists.

Secondary considerations

Objective indicia of nonobviousness must be considered when raised. They include:

• Commercial success of the patented invention, when there is a nexus between the success and the claimed features;
• Long-felt but unsolved need that the invention satisfies;
• Failure of others who attempted to solve the same problem;
• Copying by competitors, particularly those who had a license to alternatives;
• Industry praise and recognition; and
• Unexpected results.

Secondary considerations are not optional makeweight; the Federal Circuit has reversed obviousness determinations that disregarded substantial secondary-considerations evidence. Apple Inc. v. Samsung Electronics Co., 839 F.3d 1034 (Fed. Cir. 2016) (en banc). Establishing nexus between the asserted indicia and the claimed invention is the patentee's burden; a presumption of nexus may attach where the product is coextensive with the claim.

Hindsight bias

The obviousness inquiry must be conducted from the perspective of a person of ordinary skill at the time of the invention, not with the benefit of the patentee's disclosure. Graham, 383 U.S. at 36. The Federal Circuit has repeatedly cautioned against hindsight reconstruction — using the patent itself as a roadmap to identify which prior-art references to combine. The discipline imposed by requiring articulated, evidence-supported motivations to combine is the principal safeguard against hindsight.

Burden and proof

Issued patents are presumed valid under 35 U.S.C. § 282(a). An accused infringer must prove obviousness in district court by clear and convincing evidence. Microsoft Corp. v. i4i Limited Partnership, 564 U.S. 91 (2011). The Court in i4i rejected the argument that a lower preponderance standard applies when the prior art was not before the examiner, while acknowledging that an examiner's prior consideration of a reference may bear on the weight of the invalidity case.

In inter partes review, the burden is preponderance of the evidence. 35 U.S.C. § 316(e). Obviousness is a question of law reviewed de novo on appeal, with underlying factual findings — the Graham factors and motivation to combine — reviewed for substantial evidence after a PTAB decision and for clear error after a bench trial. Jury findings on the underlying factual issues are reviewed for substantial evidence.

Interaction with related doctrines

Obviousness operates alongside anticipation as the second of the novelty-related invalidity doctrines. The two share the same prior-art universe under § 102 but diverge in mechanism: anticipation requires identity in a single reference; obviousness permits combinations and asks whether differences would have been obvious. A reference that does not anticipate often grounds an obviousness theory.

Claim construction shapes obviousness as it shapes anticipation. The scope of the claim, fixed by construction, defines the differences that must be analyzed. Constructions adopted to capture an accused product can also broaden the claim against the prior art.

Obviousness intersects with written description and enablement when secondary-considerations evidence relies on commercial embodiments not coextensive with the claim. It also interacts with prosecution history estoppel, because amendments and arguments made to overcome rejections during prosecution constrain later infringement positions and may strengthen the prior-art relevance for obviousness.

Practical notes

Most validity disputes in modern patent litigation turn on obviousness. The defense is heavily expert-driven, requiring qualified witnesses on the level of ordinary skill, the disclosures of each prior-art reference, the motivation to combine, and any reasonable expectation of success. Patentees in turn marshal commercial-success and other secondary-considerations evidence supported by sales data, licensing history, copying evidence, and expert opinion on nexus.

Obviousness is the dominant ground in IPR proceedings, where the lower preponderance standard, expert PTAB judges, and concentrated prior-art focus have produced cancellation rates significantly higher than district-court invalidation rates. Petitioners must be aware of IPR estoppel, which under § 315(e) bars later assertion in district court of grounds the petitioner raised or reasonably could have raised in an instituted IPR.

In district-court litigation, obviousness is rarely resolved on summary judgment because of the layered factual inquiries and disputed expert testimony. Bench trials in Delaware and Eastern District of Texas, and jury trials in Western District of Texas, regularly turn on the credibility of the parties' experts on motivation to combine and on secondary-considerations nexus.

Open questions

The post-KSR doctrine has stabilized in broad outline but continues to generate refinement at the margins. The proper role of "common sense," the evidentiary support required for it, and its limits when used to fill gaps in the prior art are recurring issues. The Federal Circuit's treatment of "obvious to try" doctrine in unpredictable arts, particularly pharmaceuticals and biotechnology, remains case-specific and not fully reconciled. The required strength of nexus for secondary considerations to overcome a strong prima facie case of obviousness, and the application of the "blocking patent" doctrine to commercial-success evidence, continue to develop.

See also

• KSR v. TeleflexThe 2007 decision that reframed obviousness around flexibility.
• Anticipation under § 102The companion novelty doctrine that requires identity in a single reference.
• Claim constructionShapes the scope against which the prior art is measured.
• Prosecution history estoppelStatements made to distinguish prior art bind later positions.
• Inter partes reviewThe PTAB forum where obviousness challenges are most often litigated.
• IPR estoppelLimits district-court repetition of IPR grounds.
• Written description and enablementCompanion validity inquiries under § 112.

Authorities

Statutes and rules

• 35 U.S.C. § 103 (post-AIA)
• 35 U.S.C. § 103 (pre-AIA)
• 35 U.S.C. § 282(a) (presumption of validity)
• 35 U.S.C. § 315(e) (IPR estoppel)
• 35 U.S.C. § 316(e) (IPR burden)

Cases

• KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007)
• Graham v. John Deere Co., 383 U.S. 1 (1966)
• Hotchkiss v. Greenwood, 52 U.S. (11 How.) 248 (1850)
• Microsoft Corp. v. i4i Ltd. P'ship, 564 U.S. 91 (2011)
• Apple Inc. v. Samsung Elecs. Co., 839 F.3d 1034 (Fed. Cir. 2016) (en banc)
• Arendi S.A.R.L. v. Apple Inc., 832 F.3d 1355 (Fed. Cir. 2016)
• In re Van Os, 844 F.3d 1359 (Fed. Cir. 2017)
• Environmental Designs, Ltd. v. Union Oil Co. of Cal., 713 F.2d 693 (Fed. Cir. 1983)

Last reviewed: 2026