The Missing Middle Layer in Many §103 Analyses
Applicants often review an obviousness rejection by asking a binary question: did the examiner find every limitation somewhere in the cited references? That is necessary, but it is not the complete analysis.
The original CrossVision IP article described this as the “middle layer.” Reference A may contain elements 1–4 and reference B may contain element 5, yet the conclusion does not automatically follow that a skilled person would have arrived at the claimed arrangement. The examiner still needs a legally supportable path from the prior-art facts to the combination.
MPEP §2142 states the point clearly: the key to a §103 rejection is a clear articulation of why the claimed invention would have been obvious. It repeats the Federal Circuit’s formulation that conclusory statements are not enough; there must be articulated reasoning with a rational underpinning.
A sound §103 analysis needs both: factual findings about the prior art and a reason why the skilled person would have reached the claimed combination with a reasonable expectation of success.
Start with the Graham Factual Inquiries
The foundation remains the framework from Graham v. John Deere: determine the scope and content of the prior art, identify differences between the prior art and the claims, determine the level of ordinary skill, and consider objective evidence when present.
In prosecution, that means the examiner should do more than cite a column number. The Office Action should make it possible to understand what each reference is being used for, what difference remains, and how that difference is said to have been within ordinary skill.
Applicants should reconstruct these factual findings independently. A passage may mention the same noun used in a claim yet fail to disclose the claimed relationship. A reference may show the claimed result but not the mechanism. A secondary reference may disclose a feature only in an architecture that changes its function. These are factual gaps before they become legal arguments.
KSR Expanded the Available Rationales, Not the Right to Skip Reasoning
KSR v. Teleflex rejected a rigid requirement that a teaching, suggestion, or motivation to combine must be expressly found in the prior art. The USPTO therefore recognizes multiple rationales in MPEP §2143: predictable combinations, substitution, known techniques applied to similar devices, obvious-to-try reasoning, design incentives, market forces, and other explanations supported by the record.
That flexibility is sometimes misunderstood. An examiner does not have to quote a sentence saying “combine A with B,” but still must explain why a skilled person would have taken the proposed path. Common sense may be relevant; it cannot function as an unexplained conclusion.
The Stated Reason Should Fit the Evidence
When reviewing the Office Action, identify the actual rationale rather than attacking obviousness in the abstract. If the examiner says the combination improves efficiency, does the secondary reference teach that improvement? If the rationale is substitution, are the components performing comparable functions? If the rationale invokes a recognized problem, was that problem actually known at the relevant time?
A response is stronger when it shows a mismatch between the rationale and the cited evidence. For example, an examiner may say a skilled person would add a mobile carriage to increase flexibility, while the primary reference depends on fixed adjacency to achieve timing or safety constraints. That tension is more persuasive than simply saying the references are “different.”
Reasonable Expectation of Success Can Be a Separate Issue
A reason to try an approach is not always enough. The skilled person must also have a reasonable expectation that the proposed combination will achieve what the claim requires. In predictable technologies this may be relatively easy to establish. In biotechnology, chemistry, complex controls, and some software or electromechanical integrations, the record may be less predictable.
The applicant should therefore separate “why would someone attempt this?” from “why would someone reasonably expect it to work as claimed?” Conflating those questions can hide an important weakness in the rejection.
“Obvious to Try” Has Conditions
MPEP §2143 describes an obvious-to-try rationale as choosing from a finite number of identified, predictable solutions with a reasonable expectation of success. It is not a rule that every research direction worth trying is obvious.
If the examiner relies on this route, useful rebuttal questions include: Were the possible solutions actually finite and identified? Were they predictable? Did the art point toward the claimed option? Was success reasonably expected, or was substantial experimentation required to learn whether the approach worked?
Teaching Away Can Weaken the Proposed Route
If a reference criticizes, discredits, or otherwise discourages the direction proposed by the examiner, that evidence may matter. But a mere preference for one embodiment over another is not necessarily teaching away.
The strongest argument quotes the reference’s own language and explains why a skilled person, reading the art as a whole, would have been led away from the claimed path or why the proposed modification would undermine the primary reference’s intended purpose.
Do Not Forget Objective Evidence
Objective indicia—such as unexpected results, commercial success tied to the claimed features, long-felt but unresolved need, failure of others, or industry praise—can be important when the evidentiary record supports the necessary nexus. These are not decorative arguments saved for litigation. They are part of the Graham framework.
At the same time, unsupported assertions that a product was successful or that an invention was “surprising” will not carry much weight. The evidence and its connection to the claimed invention matter.
A Practical §103 Review Checklist
- Map every limitation and relationship—not merely matching nouns—to the cited art.
- Identify the examiner’s stated obviousness rationale.
- Check whether the factual findings actually support that rationale.
- Separate motivation to act from reasonable expectation of success.
- Test whether the proposed modification changes the principle or intended purpose of the primary reference.
- Look for genuine teaching-away evidence.
- Evaluate whether obvious-to-try conditions are actually satisfied.
- Consider objective evidence where a defensible nexus exists.
- Decide whether argument alone protects the desired commercial scope or whether a supported amendment is strategically better.
Takeaway
A §103 rejection is not established merely because every claim element can be found somewhere. The examiner must explain why the prior-art facts support the conclusion that the claimed arrangement would have been obvious to a skilled person.
For applicants, the most productive response often comes from testing that middle layer. Ask what the examiner’s bridge is, whether the evidence supports it, and whether the proposed combination is technically credible. That is usually more effective than arguing only that the invention “looks different.”