# 35 U.S.C. § 103: Patent Obviousness, Explained

> 35 USC 103 obviousness explained: the Graham framework, KSR's flexible test, PHOSITA, secondary considerations, and how to answer a 103 rejection.

Guide  |  Author: Lidiia Levitska  |  Source: Intellectual Property Law (outsideipcounsel.com)
Canonical: https://outsideipcounsel.com/guides/patent-obviousness-35-usc-103/


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<strong>Quick answer:</strong> [35 U.S.C. § 103](https://www.law.cornell.edu/uscode/text/35/103) bars a patent when the differences between the claimed invention and the prior art are such that the invention *as a whole* would have been obvious, before the effective filing date, to a person having ordinary skill in the art (the PHOSITA). Courts apply the factual framework of *Graham v. John Deere*: the scope and content of the prior art, the differences between the art and the claims, the level of ordinary skill, and objective indicia like commercial success and long-felt need. *KSR v. Teleflex* made the analysis flexible: examiners may rely on common sense, design incentives, and "obvious to try" logic, but must articulate reasoning with a rational underpinning, not hindsight. Obviousness is the most common reason patent applications get rejected and issued patents get invalidated. This is general education, not legal advice.
</div>

Nearly every inventor meets § 103 the same way: an office action arrives rejecting the claims over two or three references you have never heard of, "in combination." Novelty rejections are rare, because true anticipation requires one reference showing everything. **Obviousness is the real gatekeeper of the patent system**, the doctrine that separates genuine invention from routine engineering, and the ground on which most prosecution arguments, PTAB trials, and invalidity defenses are fought. This guide explains the statute, the two Supreme Court cases that define it, and what actually works when your claims are rejected. It is part of our pillar on [how to patent an idea](/guides/how-to-patent-an-idea/).

## What does Section 103 require?

The post-AIA statute is one sentence plus a coda:

> "A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, 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. Patentability shall not be negated by the manner in which the invention was made."

Four load-bearing phrases:

- **"Notwithstanding that the claimed invention is not identically disclosed."** Section 103 begins where § 102 novelty ends. Your invention can be new (no single reference shows it all) and still unpatentable because the step beyond the art was too small.
- **"As a whole."** The claim cannot be shredded into elements and each element hunted down separately; the question is whether the *claimed combination* was obvious. Dissecting a claim into its parts and finding each part somewhere in the art is the classic hindsight error.
- **"Before the effective filing date."** The AIA moved the timing question from "at the time the invention was made" to the filing date, one more reason filing early matters. (Pre-AIA applications still use the old language.)
- **"A person having ordinary skill in the art."** Obviousness is judged from the perspective of the hypothetical **PHOSITA**, not a layperson and not a genius: a practitioner presumed to know all the relevant prior art.

The final sentence abolishes any "flash of genius" requirement: how you invented (inspiration, sweat, or systematic trial) is irrelevant.

## The Graham framework: how obviousness is analyzed

*Graham v. John Deere Co.*, 383 U.S. 1 (1966), still supplies the structure every examiner and court must follow. Obviousness is a legal conclusion resting on factual inquiries:

1. **The scope and content of the prior art.** What references are analogous, meaning in the inventor's field or reasonably pertinent to the problem addressed?
2. **The differences between the prior art and the claims at issue.** Identified against the claim as a whole.
3. **The level of ordinary skill in the pertinent art.** Built from the technology's sophistication, practitioners' education, and the problems and solutions already known.
4. **Objective indicia (secondary considerations).** Commercial success, long-felt but unsolved need, failure of others, copying, industry praise, unexpected results, licensing.

The USPTO's operating manual for examiners, [MPEP § 2141](https://www.uspto.gov/web/offices/pac/mpep/s2141.html), tracks this framework verbatim and requires examiners to consider objective evidence whenever an applicant presents it.

## What did KSR v. Teleflex change?

For two decades the Federal Circuit required examiners to find an explicit **teaching, suggestion, or motivation (TSM)** in the prior art before combining references. In [*KSR International v. Teleflex*](/blog/ksr-v-teleflex-flexible-obviousness-standard/), 550 U.S. 398 (2007), a unanimous Supreme Court rejected the rigid version of that test, holding that "the combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results," and that the PHOSITA is "a person of ordinary creativity, not an automaton."

After *KSR*, examiners may support a combination with any articulated rationale that has a rational underpinning. The MPEP catalogs the accepted ones:

| KSR-era rationale | The gist |
| --- | --- |
| Combining known elements by known methods | Predictable results from a familiar combination |
| Simple substitution | Swapping one known element for another, predictably |
| Use of a known technique to improve a similar device | Same trick, same kind of device |
| Applying a known technique to a device ready for improvement | Predictable improvement |
| Obvious to try | Choosing from a finite number of identified, predictable solutions with reasonable expectation of success |
| Design incentives or market forces prompting variations | Known work adapted across fields, predictably |
| Teaching, suggestion, or motivation in the art | TSM survives as one valid rationale, not a rigid prerequisite |

The counterweight, quoted in every well-drafted response: a rejection "cannot be sustained by mere conclusory statements; instead, there must be some articulated reasoning with some rational underpinning." Common sense is allowed; hand-waving is not. And hindsight remains forbidden: the examiner may not use your patent application as the roadmap for reassembling the prior art.

## Secondary considerations: the evidence that fights back

Objective indicia exist because the *Graham* Court recognized that courtroom hindsight makes everything look inevitable. Real-world facts (the product sold enormously, the industry had tried and failed for a decade, competitors copied it, experts praised it, results surprised the field) are evidence that the step was not obvious to the people actually living in the art.

The controlling requirement is **nexus**: the objective evidence must be attributable to the *claimed, novel* features, not to marketing, price, or features the art already had. The Federal Circuit's decision in [*Yita v. MacNeil*](/blog/yita-v-macneil-secondary-considerations-nexus/) is the modern cautionary tale: commercial success driven by a feature already disclosed in the prior art carried no weight, and the claims fell. If you plan to rely on commercial success, build the evidentiary chain (sales data, testimony, marketing materials showing *which feature* drives demand) rather than asserting the conclusion.

## How to respond to a § 103 rejection, practically

An obviousness rejection is an argument, and arguments have joints. Work them in order:

1. **Audit the claim mapping.** Make a limitation-by-limitation chart of where the examiner says each element appears. A limitation missing from all cited references defeats the prima facie case by itself, and it happens more often than newcomers expect.
2. **Attack the reason to combine.** Is the motivation articulated or conclusory? Does a reference **teach away** (criticize, discredit, or discourage the claimed path)? Would the combination **destroy a reference's principle of operation** or render it unsuitable for its intended purpose? Is the "obvious to try" logic drawing from a genuinely finite set of predictable options, or from an unbounded field?
3. **Check analogous art.** A reference from a distant field is only usable if reasonably pertinent to your problem.
4. **Amend strategically.** Pull a distinguishing limitation from your specification into the claims. Narrower, allowed claims usually beat broad, rejected ones, and continuation practice preserves the broader fight for later.
5. **Submit evidence.** A declaration under 37 C.F.R. § 1.132 carrying unexpected results, comparative testing, or commercial success with proven nexus converts attorney argument into record evidence.
6. **Interview the examiner.** A 30-minute interview before responding reveals which arguments the examiner will actually accept and often produces allowable subject matter on the spot.

Two upstream moves make all of this easier. A serious [prior art search before filing](/guides/patent-search-before-filing/) lets you draft claims around the closest art instead of discovering it in an office action. And understanding where obviousness sits among the patentability requirements ([what is patentable](/guides/what-is-patentable/) covers the full set) keeps you from winning the § 103 battle while losing on eligibility or enablement.

Remember that § 103 runs both directions: after issuance, obviousness is the leading invalidity theory in district court and at the PTAB, where inter partes review petitions are built on §§ 102 and 103. If you are on the receiving end of a patent assertion, the same *Graham* and *KSR* framework is your sword; see [should you challenge a patent at the PTAB](/guides/ptab-ipr-explained/). Decisions applying the doctrine are collected in our [obviousness case archive](/topics/patents/obviousness/).

## The bottom line

Section 103 asks one question: judged as a whole, from the perspective of an ordinarily skilled, ordinarily creative practitioner who knows all the prior art, was your invention a predictable step or a real one? *Graham* supplies the factual framework, *KSR* supplies the flexible logic examiners use to combine references, and secondary considerations with a proven nexus supply the strongest counter-evidence. Most obviousness rejections are negotiable: audit the mapping, attack the reasoning, amend where the specification supports it, and put evidence, not just argument, on the record.

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*This guide is for educational purposes only and is not legal advice. IP outcomes turn on specific facts; talk to a licensed attorney about your situation.*


## Frequently asked questions

### What does 35 USC 103 actually say?

The post-AIA statute provides that a patent may not be obtained, even though the invention is not identically disclosed under section 102, 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 to which the claimed invention pertains. It adds that patentability shall not be negated by the manner in which the invention was made: insight and grinding experimentation are judged alike. Novelty under section 102 asks whether one reference shows everything; obviousness asks whether the gap between the prior art and your claim was too small to deserve a patent.

### What is a PHOSITA in patent law?

PHOSITA stands for person having ordinary skill in the art: the hypothetical practitioner from whose perspective obviousness is judged. This person is presumed to know all relevant prior art in the field at the relevant time, and after KSR is treated as a person of ordinary creativity, not an automaton, capable of combining teachings and applying common sense. The level of skill is a factual finding built from the sophistication of the technology, the education of workers in the field, the problems previously encountered, and prior solutions. Where the skill level sits can decide cases: a higher skill level makes combinations look more obvious, while a lower one makes bridging gaps in the art harder to justify.

### What are secondary considerations of nonobviousness?

Objective, real-world evidence that bears on whether an invention was actually obvious: commercial success, long-felt but unsolved need, failure of others, industry praise, licensing, copying by competitors, and unexpected results. Graham v. John Deere made them part of the framework, and the Federal Circuit requires examiners and courts to consider such evidence whenever it is presented. The catch is nexus: the evidence must be tied to the claimed invention's novel features. In Yita v. MacNeil, the Federal Circuit held that commercial success attributable to a feature already disclosed in the prior art carries no weight. Strong secondary-considerations evidence with proven nexus is one of the few tools that can rescue a claim from a solid prima facie case.

### How do I overcome an obviousness rejection?

Work the rejection's own structure. First, check that every claim limitation is actually taught by the cited references; examiners frequently gloss over one, and a missing limitation defeats the prima facie case. Second, attack the reason to combine: KSR requires articulated reasoning with rational underpinning, so conclusory motivation, hindsight reconstruction, references that teach away, or a combination that would break a reference's principle of operation are all fair targets. Third, amend to add distinguishing limitations from the specification. Fourth, submit declaration evidence of unexpected results or commercial success with nexus. An examiner interview before responding is usually the highest-value 30 minutes in prosecution.