Inherency

Inherency is a doctrine that allows a prior art reference to anticipate (§ 102) a patent claim even when the reference does not EXPRESSLY disclose a claim limitation, as long as that limitation is NECESSARILY PRESENT in the prior art as a natural result of practicing the reference. LEGAL STANDARD: In re Oelrich (CCPA 1980); Schering Corp. v. Geneva Pharmaceuticals (Fed. Cir. 2003): 'a claim limitation is inherent if it is necessarily present in the prior art, even if not explicitly recognized'; the key word is NECESSARILY — not probably, not likely, not often, but necessarily; RATIONALE: what a prior art reference makes available to the public includes not only what it explicitly discloses but also what inevitably results from practicing it; if a 1975 prior art reference describes a chemical synthesis process that necessarily produces a metabolite, and a 2023 patent claims that metabolite, the 1975 reference inherently anticipates the claim — even if the 1975 author didn't know the metabolite existed; DISCOVERY IS IRRELEVANT: a person may 'discover' that a prior art product has a property that was not previously recognized — but recognizing or discovering the inherent property is not inventive; the property was always there; CANNOT CREATE NOVELTY BY CLAIMING DISCOVERED PROPERTY: if a natural property of an old article is newly discovered, claiming that property does not create patentable novelty because the property was always inherent in the old article.

The 'necessarily present' standard is the critical threshold for inherency: NECESSARILY vs. PROBABLY: inherency requires CERTAINTY — the limitation must be necessarily, inevitably, invariably present whenever the prior art is practiced; a limitation that is PROBABLY present, USUALLY present, or OFTEN present does not meet the inherency standard; Hansgirg v. Kemmer (CCPA 1939): 'inherency may not be established by probabilities or possibilities'; PROVING NECESSARILY PRESENT: the party asserting inherency (typically the challenger in litigation, or the examiner in prosecution) must show that the undisclosed property/limitation is always produced or present when the prior art is practiced exactly as described; experimental or scientific evidence can be used; COUNTERARGUMENTS: the patent owner can rebut inherency by showing: (a) the limitation is not present in all embodiments of the prior art; (b) the prior art can be practiced without producing the limitation; (c) the inherency argument rests on a different understanding of how the prior art works; (d) the limitation requires specific process conditions not present in the prior art; RANGE OF VALUES: if the prior art discloses a process under a range of conditions, and only some conditions would produce the claimed result, inherency fails — the limitation is not necessarily present for all embodiments of the prior art; INHERENCY IN IPR: the PTAB applies the same necessarily-present standard in inter partes review; inherency arguments are common in IPR petitions for claims that add properties or results not explicitly in the prior art.

Examiners use inherency to reject claims in patent prosecution, and applicants must distinguish these rejections carefully: EXAMINER INHERENCY REJECTIONS (§ 102): examiner asserts that a prior art reference anticipates a claim limitation by inherency — e.g., if the prior art describes a composition with components A + B, and a chemical reaction between A and B necessarily produces compound C (the claimed limitation), the examiner rejects the claim as inherently anticipated; APPLICANT RESPONSE: (1) REBUT THE INHERENCY ASSERTION: argue that the limitation is NOT necessarily present — that the prior art can be practiced without producing the claimed result; provide technical reasoning or experimental data; (2) DISTINGUISH THE PRIOR ART: add claim limitations that make the inherency argument no longer applicable; (3) DEMONSTRATE DIFFERENT PROPERTIES: show that the claimed composition/method has properties the prior art does not inherently have; INHERENCY IN § 103 OBVIOUSNESS: inherency also applies to obviousness — an inherent property of a prior art reference can be relied upon to supply a missing limitation in an obviousness combination even if the property was not known to a skilled artisan; Continental Can Co. v. Monsanto (CCPA 1968); PROSECUTION HISTORY ESTOPPEL: if an applicant successfully argues against an inherency rejection by claiming the prior art CANNOT produce the claimed result, this argument may later be used as prosecution history estoppel to limit claim scope in litigation; be careful about arguments that deny properties that might be useful to claim under DOE.

Inherency arguments appear in several recurring contexts in patent litigation: (1) METABOLITE PATENTS: an innovator discovers that Drug X is metabolized in the body to Compound Y (the active metabolite); the innovator patents Compound Y; a generic challenger argues that prior art disclosing Drug X inherently anticipates Compound Y because every patient who took Drug X produced Compound Y; Schering Corp. v. Geneva Pharmaceuticals (Fed. Cir. 2003): held that the metabolite was inherently anticipated by the prior drug patent; (2) PROPERTY CLAIMS: an inventor discovers that Material A has Property P (e.g., a specific heat resistance); the prior art discloses Material A without mentioning Property P; the challenger argues Property P was always inherent in Material A and therefore the 'discovery' of Property P doesn't create a novel claim; (3) METHOD RESULT CLAIMS: a claim recites a method and also claims a result (e.g., 'a method for treating X, wherein Y is reduced by at least 20%'); the prior art discloses the same method; the challenger argues the 20% reduction was inherently achieved by the prior art method; (4) PRODUCT-BY-PROCESS CLAIMS: a claim defines a product by the process used to make it; if the prior art produces a product by an inherently similar process that gives the same product structure, inherency anticipates; (5) PHYSICAL PROPERTIES: an older product inherently has a physical property (molecular weight distribution, crystalline structure) that a newer patent claim explicitly claims — arguing discovery of the property does not create novelty.

Inherency and obviousness are distinct doctrines that operate on different theories of invalidity: INHERENCY IS ANTICIPATION (§ 102): one prior art reference alone is relied upon; the limitation is necessarily present in that single reference; no combining of references required; no motivation to combine; OBVIOUSNESS (§ 103): multiple references may be combined; the claim is not anticipatable from a single reference; a skilled artisan would have been motivated to combine references to arrive at the claimed invention; WHAT INHERENCY CANNOT DO: if a limitation is only SOMETIMES present in the prior art — i.e., some but not all embodiments produce it — inherency fails; the claim might be OBVIOUS (prior art makes it likely) but not inherently anticipated; DIFFERENT STANDARDS: inherency requires CERTAINTY (necessarily present); obviousness requires a REASONABLE EXPECTATION OF SUCCESS (not certainty); this makes inherency harder to prove but more powerful when proven (anticipation destroys the claim entirely, no secondary considerations defense); SECONDARY CONSIDERATIONS: obviousness can be overcome by secondary considerations (commercial success, long-felt need, etc.); inherent anticipation has NO secondary consideration defense — if the prior art inherently anticipates, the claim is invalid regardless of commercial success; COMBINATION INHERENCY: a limitation inherently arising from the combination of two references (not from a single reference) is an inherency argument for OBVIOUSNESS — not for § 102 anticipation; it is a proper combination under § 103.