You passed § 101—your invention is eligible subject matter with utility. You passed § 102—it's novel, not anticipated by prior art.
Now comes the hardest gate: 35 U.S.C. § 103.
Even if your invention is new (no single reference discloses it), it might still be obvious—meaning a person of ordinary skill in your field would find it obvious to combine known elements in the way you did.
§ 103 is where most patent applications die. It's the USPTO's primary weapon. And it requires you to prove not just that you created something new, but that you made an inventive leap that wasn't obvious.
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.
Key elements:
The Supreme Court established the § 103 analysis framework in Graham v. John Deere Co., 383 U.S. 1 (1966). Every obviousness determination follows these four factors:
What counts as prior art for § 103?
Analogous art test: Prior art is analogous if:
Your invention: New fishing rod design with improved grip
Examiner cites:
Result: Examiner can combine References A + B, but NOT Reference C.
Identify what's actually new. What elements or combinations are NOT in the prior art?
Critical point: If the differences are trivial, predictable, or routine optimization, likely obvious. If the differences involve unexpected results or solving a long-felt need, likely non-obvious.
Who is the "person having ordinary skill in the art" (PHOSITA)?
This is the hypothetical person from whose perspective obviousness is judged. Not a genius. Not a beginner. An ordinarily skilled practitioner.
Factors determining PHOSITA level:
Mechanical widget field: PHOSITA = person with bachelor's degree in mechanical engineering and 3-5 years of experience in widget design.
Pharmaceutical field: PHOSITA = person with PhD in medicinal chemistry or pharmacology and 5-10 years of drug development experience.
Software field: PHOSITA = person with bachelor's in computer science and 2-4 years of programming experience in relevant domain (e.g., database management, AI, etc.).
Why PHOSITA level matters: Higher skill level = broader knowledge = more combinations seem "obvious." Lower skill level = narrower knowledge = fewer combinations seem "obvious."
These are objective facts that suggest your invention was NOT obvious, even if the prior art seems close:
Critical requirement: There must be a nexus between the secondary consideration and the claimed invention. The success/praise must be due to the novel features, not other factors (e.g., marketing, brand name, unrelated features).
📖 Margin Story: The Four Questions
"Every obviousness rejection," Severen said, "answers four questions from Graham v. John Deere."
Zara counted on her fingers. "First: What does the prior art teach? Second: What's different in my claim? Third: Who is the PHOSITA judging this? Fourth: What objective evidence shows it wasn't obvious?"
"Exactly. Miss even one, and your rejection is incomplete—or your response is incomplete." His sapphire eyes gleamed. "Examiners often skip factor three—they don't define PHOSITA explicitly. That's your opening."
"I define PHOSITA narrowly. Lower skill level. Fewer combinations seem obvious."
"Smart. And factor four—secondary considerations—is your emergency weapon. Even if the prior art looks bad, commercial success or failure of others can prove non-obviousness." He paused. "The four factors are your battlefield. Learn them. Master them. Use them."
In 2007, the Supreme Court decided KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, which fundamentally changed how obviousness is analyzed.
Key holding: The analysis must be flexible. Examiners can use common sense and don't need explicit teaching in prior art for every combination.
Before KSR: Examiners had to show explicit "teaching, suggestion, or motivation" (TSM) to combine references. If prior art didn't explicitly say "combine A with B," combination was questionable.
After KSR: Examiners can rely on:
KSR identified several situations where combinations are likely obvious:
1. Combining prior art elements according to known methods to yield predictable results
"If you take Element A from Reference 1 and Element B from Reference 2, and combine them in the obvious way, and the result is exactly what you'd expect—obvious."
2. Simple substitution of one known element for another to obtain predictable results
"Replace metal spring with rubber spring? Obvious—unless unexpected results."
3. Use of known technique to improve similar devices in the same way
"If adding insulation improves refrigerators, adding insulation to coolers is obvious."
4. Applying a known technique to a known device ready for improvement to yield predictable results
"If everyone knows Widget X needs better grip, and ergonomic grips are known, combining them is obvious."
5. "Obvious to try" - choosing from a finite number of identified, predictable solutions
"If there are only three possible materials for this application, trying each one is obvious—especially if results are predictable."
6. Known work in one field prompts variations either in same field or different one if the person would be motivated to do so
"If touchscreens work on phones, trying them on tablets is obvious (market demand = motivation)."
7. Some teaching, suggestion, or motivation in prior art that would lead PHOSITA to modify or combine
"TSM test still applies—but can be implicit, not just explicit."
Critical point: KSR made it EASIER for examiners to reject claims as obvious. "Common sense" became a powerful tool. Your job: show why common sense doesn't apply, or why results were unexpected.
📖 Margin Story: After KSR
"Before 2007," Severen explained, "examiners needed explicit motivation to combine references. If Reference A didn't mention Reference B, combination was questionable."
Zara frowned. "That sounds... limiting for examiners."
"It was. Then came KSR. Supreme Court said: 'Use common sense. If a PHOSITA would obviously think to combine these elements, that's enough.' No explicit teaching required."
"So now examiners just say 'common sense' and reject everything?"
Severen's expression darkened. "Many try. Your counter: 'Examiner has not explained WHY common sense leads to this specific combination. Not all combinations are obvious just because elements are known. Show the motivation. Show the predictability. Or withdraw the rejection.'"
The flames in Zara's palm pulsed. "Force them to do the analysis. Don't let 'common sense' become a magic wand."
"Exactly. KSR allows flexibility. But it doesn't excuse lazy examination."
Although KSR made the TSM test more flexible, it's still relevant. Examiners must show there was reason to combine the prior art references.
TSM sources:
Your claim: "Widget comprising: base (from Ref A) + locking mechanism (from Ref B)."
Examiner must show TSM to combine A + B:
If examiner shows ANY of these → TSM established → Combination likely obvious
Your response: Challenge whether the cited motivation actually applies, or show unexpected results defeated the prediction
§ 103 rejections follow a structured framework. Understanding the pattern helps you spot weaknesses.
Step 1: Identify the prior art references
Step 2: Map claim elements to references
Step 3: Provide rationale for combining references
Step 4: Show results would be predictable
Step 5: State the rejection
Your claim 1:
"A beverage container comprising: (a) an insulated body maintaining temperature, (b) a lid, (c) a straw, and (d) a collapsible handle for compact storage."
Examiner's rejection:
Claim 1 is rejected under 35 U.S.C. § 103 as being obvious over Smith (U.S. Patent No. 1,111,111) in view of Jones (U.S. Patent No. 2,222,222).
Element mapping:
Rationale for combination:
It would have been obvious to a person of ordinary skill in the art to modify Smith's beverage container by incorporating Jones' collapsible handle mechanism. Smith's container is portable but bulky when stored (Smith, col. 4, lines 20-22, noting "handle extends outward, requiring additional storage space"). Jones solves this exact problem with a collapsible handle that folds flat.
One of ordinary skill would be motivated to apply Jones' collapsible handle to Smith's container to reduce storage space—a known design goal in portable products. See KSR, 550 U.S. at 417 (applying known technique to known device ready for improvement to yield predictable results).
The combination would yield predictable results: a beverage container with all of Smith's features plus space-saving storage from Jones' handle. No unexpected results. Prima facie case of obviousness established.
Notice the structure: Element mapping → Identify gap → Motivation to combine → Predictable results → Rejection stated.
§ 103 rejections are the hardest to overcome—but they have weaknesses. Attack systematically.
Goal: Show the references can't properly be combined.
Arguments:
Your invention: Pharmaceutical delivery system using microparticles
Examiner combines: Reference A (drug formulation) + Reference B (paint spray nozzle design)
Response:
"Reference B is not analogous art and cannot be combined with Reference A.
Different field of endeavor: Reference B relates to industrial paint application, not pharmaceutical delivery. See In re Klein, 647 F.3d 1343 (Fed. Cir. 2011) (references must be from same field or reasonably pertinent to problem being solved).
Not reasonably pertinent: The problem being solved is biocompatible drug delivery with controlled particle size for human injection. Paint nozzle design addresses industrial coating uniformity—fundamentally different problem with different constraints (no biocompatibility, different viscosity, different particle size requirements).
A PHOSITA in pharmaceutical formulation would not look to industrial paint equipment for solutions. The combination is improper."
Goal: Show examiner hasn't explained WHY PHOSITA would combine the references.
Common examiner failures:
Examiner states: "It would have been common sense to combine Smith's widget with Jones' material."
Response:
"Examiner has not provided sufficient reasoning for why PHOSITA would combine Smith and Jones.
Examiner relies on 'common sense' without explanation: Merely invoking 'common sense' is insufficient. Examiner must articulate specific reasoning based on rational underpinnings. See KSR, 550 U.S. at 418 ('rejections on obviousness cannot be sustained by mere conclusory statements').
Smith and Jones address different problems: Smith focuses on durability (col. 2, lines 10-15). Jones focuses on weight reduction (col. 3, lines 5-10). These are competing design goals—increasing durability typically increases weight. A PHOSITA would not 'commonly sense' to combine teachings that work against each other.
No motivation identified: Examiner has not explained what would motivate PHOSITA to select Jones' lightweight material (which sacrifices durability) for Smith's application (which prioritizes durability). Without articulated reasoning, the rejection relies on impermissible hindsight."
Goal: Prove prior art actually DISCOURAGES the combination examiner proposes.
"Teaching away" means:
Standard: Must be actual discouragement, not mere disclosure of alternative. See In re Gurley, 27 F.3d 551 (Fed. Cir. 1994).
Your claim: Pharmaceutical composition using Compound X + Compound Y together
Prior art: Reference A teaches Compound X. Reference B teaches Compound Y but states "Compound Y should not be combined with Compound X due to chemical instability."
Response:
"The prior art teaches away from the claimed combination.
Reference B explicitly warns against combining Compound Y with Compound X (col. 4, lines 15-18: 'Compound Y should not be combined with Compound X due to chemical instability'). This is not mere disclosure of an alternative—it is explicit discouragement.
A PHOSITA reading Reference B would be deterred from the very combination Examiner proposes. When prior art teaches away, a prima facie case of obviousness cannot be established. See In re Gurley, 27 F.3d 551, 553 (Fed. Cir. 1994)."
Goal: Prove the claimed combination produces results that PHOSITA wouldn't have predicted.
What qualifies as unexpected:
How to prove:
Your claim: Alloy of Metal A + Metal B in specific ratio (60:40)
Prior art: Metal A used alone. Metal B used alone. No teaching of combining them.
Your data: 60:40 ratio produces strength 5x greater than either metal alone, and 3x greater than additive prediction.
Response:
"The claimed alloy produces unexpected results that defeat any prima facie case of obviousness.
Comparative data (attached as Exhibit A):
Magnitude of unexpected result: The claimed alloy is 5x stronger than Metal A, 3.3x stronger than Metal B, and 4.2x stronger than additive prediction. This is not mere optimization—it's a synergistic effect.
Declaration from Dr. [Expert]: Attached declaration under § 1.132 explains that this level of improvement was unexpected and not predictable from the properties of the individual metals. The synergistic strengthening mechanism was unknown in the art.
Unexpected results rebut any prima facie case of obviousness. See In re Soni, 54 F.3d 746 (Fed. Cir. 1995)."
Goal: Use objective evidence to prove non-obviousness, even if prior art seems close.
Types of secondary considerations:
What to show:
Critical requirement - NEXUS: Must prove success is due to the claimed features, not marketing, brand, or unrelated features.
Example evidence: "Product launched with claimed feature. Sales increased 300% compared to prior product without feature. Competitor products lacking feature showed no similar increase. Customer reviews specifically praise the claimed feature."
What to show:
Example evidence: "Industry publications from 2010-2020 identify Problem X as major challenge. Ten different companies attempted solutions (list prior art attempts). All failed. Present invention, filed 2020, solved Problem X for the first time."
What to show:
Example evidence: "Competitor A tried combining Reference 1 with Reference 2 (as Examiner proposes). Result: product failure, recalled. Competitor B tried similar approach. Result: did not achieve claimed performance. Present invention succeeds by [explain key difference]."
What to show:
Example evidence: "Invention received [Industry Award] for innovation. Adopted as standard by [Standards Body]. Three major competitors (list) released products copying claimed features within 6 months of our launch—strong evidence of non-obviousness."
Goal: Argue for lower skill level, which makes fewer combinations "obvious."
Approach:
Examiner's implicit assumption: PHOSITA has broad knowledge across multiple technical fields
Response:
"Examiner has not properly defined the level of ordinary skill in the art, and appears to assume an unreasonably high skill level.
Proper PHOSITA definition: A person of ordinary skill in [field] would have a bachelor's degree in [discipline] and 2-4 years of practical experience in [specific area]. This is the typical educational and experience level of practitioners in this field (see Declaration of Dr. [Expert], ¶¶ 5-10).
Impact on obviousness: A PHOSITA with this level of skill would not have the broad interdisciplinary knowledge Examiner assumes. Reference B is from a specialized subfield requiring advanced expertise. A PHOSITA would not routinely consult Reference B when addressing the problem in Reference A.
With properly defined PHOSITA, the combination is not obvious."
Goal: Add feature from specification that prior art combination doesn't teach.
Best amendments:
📖 Margin Story: The Seven Weapons
"§ 103 rejections are the hardest to beat," Severen said, spreading seven stones before Zara. "But you have seven weapons."
Zara studied them. "Challenge combination. Attack motivation. Show teaching away. Unexpected results. Secondary considerations. Redefine PHOSITA. Amend claims."
"Use all seven simultaneously. Don't pick one and hope." His sapphire eyes gleamed. "Primary argument: teaching away. Alternative argument: unexpected results with data. Secondary considerations: commercial success. Backup: redefine PHOSITA to narrow knowledge. Final defense: amend claim."
The flames in her palm pulsed with each weapon named. "Force the examiner to address every argument. If one fails, five more remain."
"Exactly. § 103 rejections look strong—prior art plus prior art equals your invention. But they have seven weak points. Strike them all."
Recognize these patterns instantly on the exam:
Pattern: Your claim uses Material/Element B. Prior art uses Material/Element A. Examiner says "obvious to substitute B for A."
Example: Claim: "Widget made of aluminum." Prior art: "Widget made of steel." Examiner: "Obvious to substitute aluminum (known material) for steel."
How to overcome:
Pattern: Prior art discloses range. Your claim picks specific value within range. Examiner says "obvious optimization."
Example: Prior art: "Temperature 100-300°C." Your claim: "Temperature 180-200°C." Examiner: "Obvious to optimize within known range."
How to overcome:
Pattern: Ref A teaches problem. Ref B teaches solution to that exact problem. Examiner: "Obvious to apply B's solution to A's problem."
Example: Ref A: "Our device overheats." Ref B: "Cooling fins prevent overheating." Examiner: "Obvious to add cooling fins from B to device in A."
How to overcome:
Pattern: All elements known. Examiner: "Combination yields predictable results—obvious per KSR."
Example: Claim combines touchscreen (known) + stylus (known) + pressure sensitivity (known). Examiner: "All elements known. Combination predictable."
How to overcome:
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END OF CHAPTER 5 - OBVIOUSNESS (§ 103)