You passed § 101, § 102, and § 103. Your invention is eligible, novel, and non-obvious. Congratulations—you've proven you invented something worth patenting.
But there's one more gate: 35 U.S.C. § 112.
§ 112 governs how you disclose your invention to the public and how you claim what you own. This is the quid pro quo of the patent system:
Fail § 112, and your patent is worthless—either because you didn't teach the public enough, or because your claims don't clearly define what you own.
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
(c) FORM.—A claim may be written in independent or dependent form, and if in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
(d) REFERENCE IN DEPENDENT FORMS.—A claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
(e) REFERENCE IN MULTIPLE DEPENDENT FORM.—A claim in multiple dependent form shall contain reference, in the alternative only, to more than one claim previously set forth and then specify a further limitation of the subject matter claimed. A multiple dependent claim shall not serve as a basis for any other multiple dependent claim. A multiple dependent claim shall be construed to incorporate by reference all the limitations of the particular claim in relation to which it is being considered.
(f) ELEMENT IN CLAIM FOR A COMBINATION.—An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.
Six subsections. Each is critical. Each is independently testable. We'll cover every one.
The rule: Your specification must contain a written description of the invention sufficient to show you possessed the claimed invention at the time you filed.
Key case: Ariad Pharmaceuticals, Inc. v. Eli Lilly & Co., 598 F.3d 1336 (Fed. Cir. 2010) (en banc).
Written description is separate from enablement. It answers a different question:
Why it matters: Prevents inventors from claiming more than they actually invented by reading the prior art and then claiming broadly.
Standard: The specification must "reasonably convey to those skilled in the art that the inventor had possession of the claimed subject matter as of the filing date." Ariad, 598 F.3d at 1351.
How to show possession:
Claim: "A pharmaceutical composition comprising Compound X having formula C₁₅H₂₁NO₂."
Adequate written description:
Inadequate written description:
Result: Inadequate description = rejection. Spec doesn't show you possessed the specific compound.
Problem: You claim a broad genus (class of compounds/devices), but only describe a few specific species (examples).
Rule: For genus claim, must describe either:
Claim: "A method of treating cancer using an antibody that binds to Protein X."
Specification discloses: One specific antibody (Antibody A) that binds Protein X.
Problem: Claim covers ALL antibodies binding Protein X (millions of possible antibodies). Specification shows possession of only one.
Result: Written description rejection. See Ariad, 598 F.3d at 1350 (genus of antibodies requires more than single species unless common structure shown).
Related to written description: 35 U.S.C. § 132 prohibits introducing new matter into the specification through amendment.
"New matter" means: Information not present (expressly or inherently) in original disclosure.
Why it matters: Filing date determines priority. Adding new matter would effectively give later-invented material the earlier filing date—unfair.
📖 Margin Story: The Possession Test
"Written description," Severen said, "is the proof-of-invention test. Did you actually invent what you're claiming? Or are you claiming something you read about in prior art and now want to own?"
Zara frowned. "If I describe it in enough detail—structure, how to make it, data showing it works—that proves I possessed it?"
"Exactly. Possession requires SHOWING, not just CLAIMING. If you claim 'all antibodies binding Protein X' but only describe one antibody, you're claiming millions of things you never possessed."
The flames in her palm shifted. "But if I claim that one antibody I actually made—"
"Then written description is satisfied. You possessed it. You described it. The claim matches the possession." His sapphire eyes gleamed. "The quid pro quo works: You taught the public what you invented. Now you can claim it."
The rule: The specification must teach PHOSITA how to make and use the full scope of the claimed invention without undue experimentation.
Key case: In re Wands, 858 F.2d 731 (Fed. Cir. 1988).
Enablement asks: Can a PHOSITA, reading your specification, make and use the invention across its entire claimed scope without undue experimentation?
In re Wands established 8 factors for determining whether experimentation is "undue":
Analysis is totality of circumstances—no single factor is dispositive.
How much work does PHOSITA need to do to make/use the invention?
Does the spec provide detailed instructions, or just vague generalities?
Does the spec include actual examples showing the invention works?
Simple mechanical device vs. complex biotech? Nature affects experimentation burden.
If prior art provides background knowledge, less detail needed in your spec.
Higher skill = can fill in more gaps with their knowledge = less detail needed.
This is critical:
Critical enablement principle: Scope of enablement must match scope of claims.
Claim: "A method of treating cancer using a compound of formula [genus covering 10,000 compounds]."
Specification discloses: Synthesis method for the genus. Testing data for 3 specific compounds showing anti-cancer activity.
Analysis:
Result: Likely NOT enabled. Spec enables the 3 tested compounds, but not the full genus. Applicant must either (1) test more compounds and add data, or (2) narrow claims to enabled species.
Dangerous practice: Claiming based on predicted results rather than actual data.
Rule: In unpredictable arts (biotech, pharma, chemistry), prophetic examples often insufficient for enablement. See In re '318 Patent Infringement Litig., 583 F.3d 1317 (Fed. Cir. 2009).
📖 Margin Story: The Teaching Burden
"Enablement," Severen explained, "is the teaching requirement. You claim it, you teach it. All of it."
Zara studied the Wands factors. "If I claim a genus of 10,000 compounds but only test 10—"
"Then you've enabled 10 compounds. Not 10,000." His sapphire eyes gleamed. "In unpredictable arts, you can't extrapolate. Each compound behaves differently. Testing 10 doesn't teach how to make the other 9,990 work."
"So narrow the claim to match the data."
"Or generate more data to support the broader claim. But you can't claim more than you enable." He paused. "Breadth of claims must match breadth of enablement. Always."
The rule: You must disclose the best mode of carrying out the invention that you knew at the time of filing.
Two-part test:
What you must disclose:
What you don't need to disclose:
Important: After September 16, 2012 (AIA effective date), failure to disclose best mode is NOT a ground for invalidity in litigation or post-grant proceedings.
BUT: Best mode is still required during prosecution. Examiner can reject for lack of best mode. Applicant must still disclose it.
Practical impact: Less emphasis on best mode in modern practice, but still technically required.
The rule: Claims must "particularly point[] out and distinctly claim[]" the subject matter regarded as the invention.
This breaks into two separate requirements:
Key case: Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898 (2014).
Test: A claim is definite if it "inform[s] those skilled in the art about the scope of the invention with reasonable certainty." Nautilus, 572 U.S. at 910.
Note: Nautilus replaced the older "insolubly ambiguous" standard (which was too lenient). New standard is stricter.
1. Subjective Terms
Indefinite: "A chair having an aesthetically pleasing design."
→ What's "aesthetically pleasing"? Subjective. No objective boundary. PHOSITA can't determine scope with reasonable certainty.
Definite: "A widget having a temperature of about 100°C."
→ "About" means approximately, perhaps ±5-10°C based on context/prior art. PHOSITA can determine scope with reasonable certainty.
2. Relative Terms Without Reference
3. Unclear Antecedent Basis
Each term in a claim must have clear antecedent basis—the first time a term appears, use "a" or "an"; subsequent references use "the" or "said."
Claim: "A widget comprising: a base, a rotating arm, wherein the spring connects the arm to the base."
Problem: "THE spring" appears without prior introduction. No "a spring" earlier in claim. What spring? Indefinite.
Fix: "A widget comprising: a base, a rotating arm, a spring connecting the arm to the base."
4. Functional Language Without Structure (addressed in § 112(f))
The rule: Claims can be written in independent or dependent form.
Definition: Stand-alone claim that doesn't refer to any other claim.
Form: "A [device/method/composition] comprising..."
Scope: Broadest claim—includes only essential elements.
Definition: Claim that refers back to and further limits another claim.
Form: "The [device/method/composition] of claim X, wherein..." or "The [device/method/composition] of claim X, further comprising..."
Key rule: Dependent claim incorporates by reference ALL limitations of the claim it depends from.
Claim 1 (independent): A widget comprising: (a) a base, (b) a rotating arm, and (c) a spring.
Claim 2 (dependent): The widget of claim 1, wherein the spring is made of steel.
Claim 3 (dependent): The widget of claim 2, further comprising a locking mechanism.
Claim 2 includes:
Claim 3 includes:
The rule: A dependent claim must:
Must add a limitation:
Must reference previously set forth claim:
The rule: A multiple dependent claim references more than one previous claim in the alternative.
Proper format: "The widget of claim 1 or 2, wherein..."
Key restrictions:
Claim 1 (independent): A widget comprising a base and an arm.
Claim 2 (dependent): The widget of claim 1, wherein the base is circular.
Claim 3 (dependent): The widget of claim 1, wherein the arm is rotating.
Claim 4 (multiple dependent - PROPER): The widget of claim 1 or 2, further comprising a spring.
→ This reads as two claims: (1) widget of claim 1 + spring, OR (2) widget of claim 2 + spring
Claim 5 (IMPROPER): The widget of claim 4 or 3, further comprising a handle.
→ IMPROPER: Claim 5 is multiple dependent (references 4 or 3). Claim 4 is also multiple dependent. § 112(e) prohibits this—multiple dependent claim cannot serve as basis for another multiple dependent claim.
Important: Each alternative in a multiple dependent claim counts as a separate claim for fee purposes.
Example: "The widget of claims 1, 2, or 3..." counts as 3 claims for fees (one for each alternative).
The rule: You can claim an element as a "means" or "step" for performing a function WITHOUT reciting structure—BUT such claims are construed to cover only:
Triggers for § 112(f) interpretation:
MPF claim element: "means for connecting the base to the arm"
→ Uses "means," describes function (connecting), no structure. § 112(f) APPLIES.
How it's construed: Look to specification to find what structure performs "connecting" function.
Spec discloses: "The base and arm are connected by a threaded bolt 10 passing through aligned holes."
MPF claim limited to: Threaded bolt (as described) + equivalents (e.g., different bolt type, rivet, pin - NOT welding, glue, or fundamentally different connection methods).
Problem: MPF claims are construed NARROWLY—limited to disclosed structure + equivalents.
If you don't want MPF interpretation:
MPF (narrow): "means for connecting the base to the arm"
Non-MPF alternative (broader): "a fastener connecting the base to the arm"
→ "Fastener" is structural term (not pure function). Covers bolts, rivets, pins, clips, etc. Broader than MPF.
Non-MPF alternative (even broader): "a connector connecting the base to the arm"
→ "Connector" is generic structural term. Covers mechanical fasteners, adhesives, welds, etc. Very broad.
📖 Margin Story: The MPF Trap
"Means-plus-function claiming," Severen warned, "is a trap. Looks broad. Actually narrow."
Zara frowned. "'Means for connecting' sounds like it covers ANY way to connect."
"That's what applicants think. But § 112(f) limits it to the structure you disclosed PLUS equivalents. If your spec shows a bolt, your MPF claim covers bolts and bolt-equivalents—not adhesives, not welds, not completely different connection methods."
"So I should just say 'a connector' instead of 'means for connecting'?"
"Yes. Generic structural term. Broader scope. No § 112(f) limitation." His sapphire eyes gleamed. "Only use MPF if you WANT narrow scope—like when broad claim would read on prior art. Otherwise, avoid it."
§ 112 rejections require different strategies depending on which subsection is at issue.
Strategy 1: Point to Original Disclosure
Strategy 2: Expert Declaration (37 C.F.R. § 1.132)
Strategy 3: Amend Claims to Match Disclosure
Strategy 1: Address Wands Factors
"Applicant respectfully traverses the enablement rejection. Analysis of the Wands factors shows enablement is satisfied:
Totality of circumstances shows enablement without undue experimentation."
Strategy 2: Submit Additional Data (37 C.F.R. § 1.132)
Strategy 3: Narrow Claims to Enabled Scope
Strategy 1: Explain Term Using Specification
Strategy 2: Rely on Prior Art Understanding
Strategy 3: Amend for Clarity
Pattern: Claim broad genus. Spec discloses only a few species.
Example: Claim 10,000 antibodies. Spec describes 3.
Rejections:
How to overcome:
Pattern: Spec contains only prophetic (hypothetical) examples. No actual working data.
Example: "One skilled in the art could use Compound X to treat Disease Y..."
Rejection: In unpredictable art (biotech), prophetic examples insufficient. Must show it actually works.
How to overcome:
Pattern: File continuation adding new claims not supported by parent application.
Example: Parent app describes Widget with Metal A. Continuation claims Widget with Metal B (not mentioned in parent).
Rejection: New matter (§ 132). Parent didn't describe Metal B. Claims lack written description support as of parent's filing date.
How to overcome:
Pattern: Claim uses subjective or relative terms without objective standard.
Examples:
Rejection: Indefinite under § 112(b). PHOSITA can't determine scope with reasonable certainty.
How to overcome:
📖 Margin Story: The Quid Pro Quo
"Section 112," Severen said, gesturing to all six subsections, "is the contract between you and society."
Zara studied them. "Written description proves I possessed what I'm claiming. Enablement teaches the public how to make and use it. Claims define what I own."
"Exactly. You can't claim what you didn't possess. You can't claim more than you taught. And you can't claim indefinitely—boundaries must be clear." His sapphire eyes gleamed. "Break any part of § 112, and the contract fails. Either you didn't give enough (enablement, written description), or you claimed too much (scope exceeds disclosure), or your boundaries are unclear (definiteness)."
The flames in her palm burned steady. "So every rejection has a fix. Point to disclosure. Add data. Narrow claims. Define terms."
"Yes. But the real lesson: draft correctly from the start. Broad disclosure. Working examples. Clear claims. Fix § 112 before filing, not during prosecution."
She nodded. "Prevention over cure."
"Always."
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END OF CHAPTER 6 - SPECIFICATION AND CLAIMS (§ 112)
END OF BOOK 3: THE LABYRINTH OF LAW AND LIES
Four Gates Mastered: § 101, § 102, § 103, § 112