USPTO guide
How to respond to a 35 U.S.C. 103 rejection
By Dharmik Patel, Co-founder, PatentAssist.ai
Updated
Obviousness is the rejection you will see most, and the one with the most room to argue. The examiner usually admits the main reference is missing something, borrows it from a second reference, and gives a reason a skilled person would have combined the two. Each of those steps is a factual finding you can test. This guide explains what the examiner must establish under MPEP 2141 to 2145, how to take the rejection apart, which arguments work and which do not, and how to build evidence of non-obviousness. For deadlines and reply format, see the parent guide on responding to a USPTO office action.
Quick answer
- The framework: the Graham factual inquiries plus a reason to combine with "articulated reasoning with some rational underpinning" (MPEP 2141, 2142).
- Strongest arguments: a limitation missing from the combination; a modification that would make the primary reference unfit for its purpose or change its principle of operation (MPEP 2143.01); no reasonable expectation of success (2143.02).
- Teaching away needs a reference that discourages your solution, not one that merely prefers another.
- Evidence: unexpected results, commercial success and other objective indicia, with nexus to the claims, by Rule 132 declaration (MPEP 716).
What the examiner must show
35 U.S.C. 103 bars a patent if the differences between the claim 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. Under Graham v. John Deere (1966), as set out in MPEP 2141, the examiner resolves three factual questions: the scope and content of the prior art, the differences between the art and the claim, and the level of ordinary skill. Objective evidence of non-obviousness is weighed too when it is in the record.
KSR v. Teleflex (2007) made the analysis flexible: the reason to combine need not be written in the references. It did not make it optional. Rejections "cannot be sustained by mere conclusory statements; instead, there must be some articulated reasoning with some rational underpinning" (MPEP 2142, quoting In re Kahn). The examiner must also consider every limitation of the claim (MPEP 2143.03), use art that is analogous (2141.01(a)), and have a basis for expecting the combination to succeed (2143.02). Once a prima facie case is made, the burden moves to you to rebut it with argument or evidence.
Art is analogous if it is from the same field of endeavor as your invention, even if it addresses a different problem, or if it is reasonably pertinent to the problem you faced, even if from another field. These are two separate tests and the reference only has to pass one (In re Bigio, MPEP 2141.01(a)). A nonanalogous art argument works best when the reference is from a different field and solves an unrelated problem.
The KSR rationales in MPEP 2143
MPEP 2143 lists seven example rationales. Examiners often name one by its letter. Each comes with findings the examiner must make, and those findings are where to look for a gap. The list is not exhaustive.
| Rationale | Where to push back |
|---|---|
| (A) Combining prior art elements according to known methods to yield predictable results | Is every element really in the art, and would the combination behave as each part did alone? Synergy or interaction between the parts undercuts "predictable". |
| (B) Simple substitution of one known element for another to obtain predictable results | Was the substitute known to perform the same function in this context? If substituting it changes how the device works, it is not simple. |
| (C) Use of a known technique to improve similar devices, methods or products in the same way | Is the base device actually similar, and is the improvement the same kind as in the reference? |
| (D) Applying a known technique to a known device, method or product ready for improvement to yield predictable results | Was the base ready for that improvement, or would it need redesign the examiner has not accounted for? |
| (E) "Obvious to try": choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success | Were the options really finite and identified? Was the art predictable? Many variables or unpredictable chemistry and biology weaken it. |
| (F) Known work in one field prompting variations for use in the same or another field, based on design incentives or market forces, if the variations are predictable | Does the examiner identify the actual incentive, with evidence, or just assert one? |
| (G) Some teaching, suggestion or motivation in the prior art to modify or combine references | Read the cited passage. Does it suggest the modification you claim, or something else? |
How to read the rejection
- Find the admission. Most 103 rejections say "Smith does not explicitly teach X." That sentence tells you what the examiner thinks your invention adds. Everything else in Smith has been found against you, so check those findings too.
- Read the secondary reference in context. Does it teach X as claimed, in an arrangement that would fit Smith, or something that only shares the word?
- Isolate the reason to combine. Copy the "because" sentence. Is it a generic benefit ("to improve efficiency") that would justify any change, or a specific reason tied to Smith's problem?
- Picture the modified device. Would Smith still work? Would it still do what Smith built it to do?
- Look for official notice. "It is well known that..." without a reference is official notice and must be traversed in this reply if you disagree (MPEP 2144.03).
- Check the dependent claims. They are often rejected with a sentence each. A dependent claim with a real distinction is a ready amendment.
Pull the full text of each reference rather than relying on the passages quoted. A free US patent search gives the full text, claims and family of cited patents. If a reference was cited under 102 first, see the 102 rejection guide on whether it qualifies as prior art at all; the same date rules and exceptions apply to 103.
Arguments that work
The combination still lacks a limitation
The cleanest argument. If neither reference, nor the combination as the examiner proposes it, has a limitation, there is no prima facie case (MPEP 2143.03). Address the combination, not each reference alone: say what Smith lacks, what Jones lacks, and why putting them together still does not give the claimed arrangement.
Unfit for its purpose, or a changed principle of operation
If the proposed modification would make the primary reference unsatisfactory for its intended purpose, there may be no motivation to make it (In re Gordon, MPEP 2143.01, subsection V). If it would change the reference's principle of operation, the references are not sufficient to make the claim prima facie obvious (In re Ratti, subsection VI). These are strong when the secondary feature only works by abandoning the very mechanism the primary reference relies on.
No reasonable expectation of success
Obviousness requires a reasonable expectation of success (MPEP 2143.02), judged before the effective filing date. In predictable mechanical arts this rarely wins. In chemistry, biology and some machine learning work, where small changes have unpredictable effects, evidence of that unpredictability can carry the argument.
Teaching away
A reference that teaches away is a significant factor, but the bar is high. Under MPEP 2145, subsection X.D, disclosing more than one alternative is not teaching away from any of them (In re Fulton), and a general preference for something else is not enough unless the reference criticizes, discredits or otherwise discourages the claimed solution (UCB v. Actavis, 2023). Being described as somewhat inferior is also not enough (In re Gurley). Quote the discouraging passage word for word.
Hindsight, shown concretely
A bare "hindsight" objection fails. What works is showing that the examiner's reason to combine is your own problem statement: the stated motivation appears nowhere in the references and matches your specification's description of the problem. Then the reconstruction draws on knowledge gleaned only from your disclosure, which In re McLaughlin (quoted in MPEP 2145, subsection X.A) says is improper.
Arguments that rarely work
| Argument | Why it fails |
|---|---|
| Attacking each reference on its own | When the rejection combines references, say what the combination lacks, not what each reference lacks (MPEP 2145, subsection IV). |
| Counting the references | Using many references does not, without more, show non-obviousness (MPEP 2145, subsection V). |
| Pointing to the age of the references | Age alone is not persuasive (MPEP 2145, subsection VIII), though it can support a long-felt need showing with evidence. |
| Relying on features that are not in the claim | Limitations in the specification are not read into the claims (MPEP 2145, subsection VI). Amend if the feature matters. |
| Saying the parts could not be physically combined | The test is what the combined teachings would have suggested, not whether parts bolt together (MPEP 2145, subsection III). |
| Lawyer's assertions of unexpected results | Argument does not replace evidence where evidence is needed (MPEP 2145, subsection I). Put the data in a declaration. |
Argue or amend
Argue without amending when you have a missing limitation, a broken primary reference, or a reason to combine that is nothing but your own disclosure. Amend when the examiner's reading is fair and your claim is simply broad. The best amendment adds a feature that ties to why the invention works, so the argument and the amendment support each other. Before you choose it, search for that feature; adding a limitation that a third reference discloses only buys one more round.
Rejected over Smith (a passive heat sink with fins) in view of Jones (a heat pipe). Underlining marks added text and strike-through marks deleted text.
1. (Currently amended) A cooling assembly for a
processor, comprising:
a base plate in contact with the processor;
a plurality of fins extending from the base plate; and
a heat pipe having an evaporator section embedded in the base
plate and a condenser section in the fins passing through the fins, wherein the fins are
spaced at a pitch that decreases from the evaporator
section toward a distal end of the condenser
section, such that fin density is highest where
vapor temperature in the heat pipe is lowest.
The Office action proposes adding Jones's heat pipe to Smith "to improve heat transfer." Smith's assembly works by natural convection through a central chimney formed by the open space between its fin arrays (col. 3, lines 5-30; FIG. 2). Routing a heat pipe through the fins, as claimed, requires filling that chimney, which removes the airflow path Smith relies on. The proposed modification would change Smith's principle of operation and is therefore insufficient to establish a prima facie case. In re Ratti, 270 F.2d 810 (CCPA 1959); MPEP 2143.01, subsection VI. Further, neither Smith nor Jones, alone or combined, teaches fins at a pitch that decreases along the condenser section, as amended claim 1 requires.
Illustrations only. The references and passages are invented, and every amendment needs support in the application as filed.
Secondary considerations and nexus
Objective evidence of non-obviousness must be considered when it is timely presented (MPEP 716.01(a)). It is weighed with the evidence for obviousness, not as an afterthought. The types recognized in MPEP 716:
| Evidence | MPEP | What you need |
|---|---|---|
| Unexpected results | 716.02 | Data showing a difference in kind or degree that a skilled person would not have expected, compared with the closest prior art, and commensurate in scope with the claims. |
| Commercial success | 716.03 | Sales or market share figures, plus proof that the success comes from the claimed features rather than marketing, price or brand. |
| Long-felt need and failure of others | 716.04 | Evidence the need was recognized and persistent, that others tried and failed, and that your invention met it. |
| Skepticism of experts | 716.05 | Contemporaneous statements by people in the field doubting the approach would work. |
| Copying | 716.06 | More than a competitor selling a similar product: evidence of efforts to replicate a specific product, such as internal documents or reverse engineering (Wyers v. Master Lock). |
Nexus is where most evidence fails. It is the "factually and legally sufficient connection" between the evidence and the claimed invention, and you bear the burden of showing it (MPEP 716.01(b), citing Demaco and In re Huang). Nexus is presumed when the evidence is tied to a specific product that embodies the claimed features and is coextensive with them (Fox Factory v. SRAM, 2019). A product with many unclaimed selling points, or a claim much broader than the product, weakens the presumption. Unexpected results must be compared with the closest prior art (716.02(e)) and be commensurate in scope with the claim (716.02(d)); a result shown for one compound rarely supports a claim to a class of thousands.
Rule 132 declarations
Evidence to traverse a rejection goes in by declaration under 37 CFR 1.132. The examiner weighs an expert opinion by the nature of the matter, the strength of opposing evidence, the declarant's interest in the outcome, and the factual support given (MPEP 716.01(c)). An inventor may sign, but a disinterested expert with data carries more weight. Opinions on the ultimate legal question of obviousness carry little.
- Declarant's qualifications and relationship to the applicant.
- The closest prior art (Smith, Example 3) and why it is the closest.
- Test method: samples made per Smith Example 3 and per claim 1 at both ends of the claimed range, same conditions, repeated three times.
- Results in a table, with the measured difference and its variability.
- Why a skilled person, before the effective filing date, would not have expected that difference, citing publications from that time.
- Why the results represent the full scope of claim 1.
Timing matters. Evidence filed before a final rejection is entered. After final it is entered only on a showing of good and sufficient reasons why it was necessary and not earlier presented (37 CFR 1.116(e)), or with an RCE, which reopens prosecution. If you know evidence will be needed, file it with the first reply.
Common mistakes
- Arguing references individually when the rejection combines them. Address what the combination teaches.
- Saying "hindsight" without more. Every obviousness analysis is a reconstruction; it is improper only if it uses knowledge taken from your disclosure (MPEP 2145, subsection X.A). Show what the examiner took from your application.
- Calling a mere preference in the art a teaching away. A reference that lists alternatives or prefers another option does not teach away unless it criticizes, discredits or discourages yours (MPEP 2145, subsection X.D).
- Submitting results that compare the invention with something other than the closest prior art, or that cover one embodiment of a broad claim.
- Not traversing official notice in the next reply. If you do not specifically challenge a noticed fact, it may be taken as admitted prior art (MPEP 2144.03).
- Narrowing the claim more than needed. Remarks and amendments made to overcome art can limit the claim later through prosecution history estoppel.
Claims built with layered fallback features are far easier to defend against obviousness; see how to write patent claims. Any amendment must also satisfy 112(a) support, covered in the 112 rejection guide, and if a 101 rejection came in the same action, see the 101 rejection guide.
Where PatentAssist helps
PatentAssist.ai does not write USPTO office action responses. Its office action feature supports Indian First Examination Reports only, in beta. For a 103 rejection, the useful parts are the free prior-art search across USPTO, EPO and Indian records, to read the cited references in full and check whether your proposed amendment is already in a third reference, and the drafting tool, which writes USPTO-format specifications and claims with the fallback features that give you somewhere to retreat to.
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35 U.S.C. 103 rejections: frequently asked questions
What is a 35 U.S.C. 103 rejection?
It is an obviousness rejection: the examiner says the differences between your claim and the prior art are such that the claimed invention as a whole would have been obvious to a person of ordinary skill in the art before the effective filing date. Usually it combines two or more references, or modifies one. The framework is in MPEP 2141 to 2145.
How do I overcome a 103 rejection?
Check each finding. Does the combination actually teach every limitation? Does the examiner give an articulated reason to combine with a rational underpinning? Would the modification make the primary reference unfit for its purpose or change its principle of operation? Would a skilled person have expected success? Then amend to a feature the art does not suggest if needed, and add objective evidence such as unexpected results by declaration under 37 CFR 1.132.
What are the KSR rationales?
MPEP 2143 lists seven example rationales drawn from KSR v. Teleflex (2007): (A) combining known elements by known methods for predictable results; (B) simple substitution; (C) a known technique used to improve similar devices; (D) a known technique applied to a known device ready for improvement; (E) obvious to try; (F) known work prompting variations through design incentives or market forces; and (G) a teaching, suggestion or motivation in the art. The list is not exhaustive.
What counts as teaching away?
A reference teaches away when it criticizes, discredits or otherwise discourages the solution you claim. Merely disclosing alternatives, or preferring a different option, is not teaching away (In re Fulton; UCB v. Actavis, cited in MPEP 2145). Describing your approach as somewhat inferior is also not enough on its own (In re Gurley).
What is nexus for secondary considerations?
Nexus is the link between the objective evidence, such as commercial success, and the merits of the claimed invention. You bear the burden of showing it (MPEP 716.01(b)). It is presumed when the evidence is tied to a specific product that embodies the claimed invention and is coextensive with it (Fox Factory v. SRAM, 2019). If the success comes from unclaimed features, the evidence carries little weight.
Can I use a Rule 132 declaration to overcome obviousness?
Yes. Evidence of unexpected results, commercial success, long-felt need, skepticism or copying, and expert testimony about what a skilled person would have understood, goes in a declaration under 37 CFR 1.132. File it before a final rejection if you can. After final it is entered only on a showing of good and sufficient reasons why it was not presented earlier, or with an RCE.
Can an examiner rely on official notice in a 103 rejection?
Only for facts that are capable of instant and unquestionable demonstration as well known. To challenge it, specifically point out why the noticed fact is not common knowledge; a bare demand for evidence is not enough. If you traverse adequately, the examiner must provide documentary evidence in the next action to maintain the rejection (MPEP 2144.03).
Sources: 35 U.S.C. 103 (see our annotated obviousness statute and KSR notes); 37 CFR 1.132; MPEP 716, 2141, 2142, 2143, 2144 and 2145 (Ninth Edition, Revision 01.2024). Checked October 26, 2026. This guide is general information, not legal advice. Have a registered patent attorney or agent review your reply.