Patent Litigation

Patent Invalidity Defense

Invalidity is the complete defense to patent infringement — if the patent should never have been granted, there is nothing to infringe. Clear and convincing evidence is required, but the grounds are varied and powerful.

What is a patent invalidity defense and when does it apply?

A patent invalidity defense argues that the patent-in-suit should never have been granted — that it fails to meet the legal requirements for patentability.

Every Accused Infringer has Standing to Challenge Validity

Even a defendant who admits infringement can argue the patent is invalid
Invalidity is a complete defense — if the patent is invalid, there is nothing to infringe

Presumption of Validity

35 U.S.C. § 282 establishes a presumption that issued patents are valid
Challengers must overcome this presumption by clear and convincing evidence (Microsoft Corp. v. i4i, S.Ct. 2011)

Clear and Convincing Evidence

Higher than preponderance of the evidence (more likely than not)
Requires that the evidence leave the fact-finder with a high degree of confidence the patent is invalid

Contrast with PTAB. IPR and PGR proceedings at the PTAB apply a preponderance of the evidence standard (lower) — one reason IPR cancellation rates exceed district court invalidity rates

Invalidity Grounds

(a) § 102 ANTICIPATION: a single prior art reference discloses every element of the claimed invention
(b) § 103 OBVIOUSNESS: the claimed invention would have been obvious to a POSITA given the prior art
(c) § 101 PATENT INELIGIBILITY: the claim is directed to an abstract idea, law of nature, or natural phenomenon without adding significantly more (Alice/Mayo)
(d) § 112(a) WRITTEN DESCRIPTION: the specification does not demonstrate that the inventor possessed the claimed invention
(e) § 112(a) ENABLEMENT: the specification does not teach a POSITA how to make and use the claimed invention without undue experimentation
(f) § 112(b) INDEFINITENESS: the claims do not inform a POSITA of the scope with reasonable certainty (Nautilus)
(g) INEQUITABLE CONDUCT: the patent was obtained through fraud on the USPTO
Renders the patent unenforceable (not invalid per se, but functionally equivalent).

How is a prior art anticipation defense structured under § 102?

Anticipation under § 102 requires that every element of the claimed invention be present in a single prior art reference.

Anticipation Elements

(a) the prior art reference must have been available before the patent's effective filing date
(b) the reference must disclose EVERY element of the claim, either explicitly or inherently
(c) the reference must disclose the elements arranged as in the claim — not scattered across different embodiments
TYPES OF PRIOR ART (AIA § 102(a)): § 102(a)(1): public disclosures before the effective filing date — patents, publications, public use, on-sale offers, and other public disclosures anywhere in the world
§ 102(a)(2): earlier-filed but unpublished US/PCT applications (secret prior art) — effective as of their filing date
AIA EXCEPTIONS (§ 102(b)): disclosures by the inventor within 1 year of filing do not count as prior art
Disclosures made after an inventor's earlier public disclosure are not prior art
Common ownership exception for § 102(a)(2) (internal company filings)

Inherent Anticipation. An element is inherent in the prior art if it necessarily follows from the disclosed elements, even if not explicitly described

Claim Chart

An anticipation defense requires a detailed claim chart showing where each claim element appears in the prior art reference
Element-by-element mapping
Expert testimony explains how the prior art discloses each element to a POSITA

Single Reference Requirement

If elements are split across two references, this is NOT anticipation — it may be obviousness
Anticipation requires one reference with everything
PRE-AIA vs.

AIA

For patents with effective filing dates before March 16, 2013, the pre-AIA § 102 (a), (b), (e), (f), (g) applies
For patents with effective filing dates on or after March 16, 2013, the AIA § 102 applies.

How is an obviousness invalidity defense structured under § 103?

Obviousness is the most commonly asserted invalidity defense — and the most complex: GRAHAM v. JOHN DEERE (S.Ct. 1966): four-factor test: (1) scope and content of the prior art; (2) differences between the prior art and the claims; (3) level of ordinary skill in the pertinent art (POSITA); (4) secondary considerations; KSR INTERNATIONAL v. TELEFLEX (S.Ct. 2007): rejected rigid TSM (teaching-suggestion-motivation) test; adopted flexible, expansive view of prior art combinations; a POSITA is 'a person of ordinary creativity, not an automaton';.

Combinations

Obviousness is typically based on combining multiple prior art references
The question is whether a POSITA would have been motivated to combine references with a reasonable expectation of success

Motivation to Combine. Can be found in the prior art references themselves, the knowledge of a POSITA, the nature of the problem being solved, or known design choices

Teaching Away. If a prior art reference explicitly warns against the claimed combination, this is evidence against obviousness

Obviousness Claim Chart

Shows which elements come from which prior art references
Expert testimony explains the motivation to combine

Secondary Considerations. Commercial success (with nexus), long-felt need, failure of others, unexpected results, expert skepticism — all must be considered

Burden Shifting. After the defendant presents prima facie evidence of obviousness, the burden shifts to the patentee to present secondary considerations and argue against obviousness

Dependent Claims. Even if an independent claim is obvious, dependent claims adding specific limitations may be patentable if those specific limitations are not obvious.

What are § 112 invalidity defenses and how are they used?

Section 112 provides multiple distinct invalidity defenses related to the specification's support for the claims: § 112(a) WRITTEN DESCRIPTION: the specification must demonstrate that the inventor actually possessed the claimed invention at the time of filing; applicable when: claims are broader than what was specifically disclosed; continuation or CIP claims assert priority to an earlier application that didn't disclose the claimed subject matter; functional genus claims lack structural support for the full scope; Ariad Pharmaceuticals v. Eli Lilly (Fed. Cir. 2010 en banc): written description is a separate requirement from enablement; § 112(a) ENABLEMENT: the specification must teach a POSITA how to make and use the full scope of the claimed invention without undue experimentation; Amgen v. Sanofi (S.Ct. 2023): functional genus claims covering millions of variants require specification support enabling the full genus; Wands 8-factor test for undue experimentation; § 112(b) INDEFINITENESS: claims must inform a POSITA of the claim scope with reasonable certainty (Nautilus v. Biosig, S.Ct. 2014); subjective terms without objective specification anchors are vulnerable; hybrid apparatus + method claims (IPXL Holdings); antecedent basis failures; § 112(f) MEANS-PLUS-FUNCTION: 'means for' language invokes MPF interpretation; if no corresponding structure is disclosed in the specification for the claimed function, the claim is indefinite; Aristocrat Techs v. IGT (Fed. Cir. 2007): software MPF claim must disclose the specific algorithm;.

Where to Raise

District court (any § 112 ground)
PGR (§ 112 grounds, within 9 months of grant)
IPR does NOT allow § 112 challenges
§ 112 defenses are raised in invalidity contentions and litigated through expert testimony.

What is inequitable conduct and how does it differ from invalidity?

Inequitable conduct renders a patent UNENFORCEABLE — a stronger remedy than invalidity.

Definition

Inequitable conduct is an equitable defense that applies when the patent was procured through fraud on the USPTO
The patentee (inventor or patent counsel) deliberately withheld or misrepresented material information with intent to deceive the USPTO examiner
THERASENSE (Fed. Cir. 2011 en banc): established the current strict standard

Two Elements Both Required

(a) MATERIALITY: but-for materiality standard — the USPTO would not have allowed the patent if it had known the withheld information
A reference is but-for material if there is a substantial likelihood that the examiner would have rejected the claims had the reference been disclosed
Exceptions: references cumulative to already of record prior art
(b) SPECIFIC INTENT TO DECEIVE: the patentee knew about the material information
Knew it was material
Made a deliberate decision to withhold or misrepresent it

Specific Intent Cannot be Inferred from Gross Negligence Alone. Must be based on clear and convincing evidence of intentional deception

Unclean Hands Doctrine. Even without meeting the full Therasense test, extreme patentee misconduct can trigger unclean hands defense rendering the patent unenforceable

What it Applies to

Failing to disclose known prior art during prosecution
Submitting a false declaration (false inventor oath, false affidavit of prior commercial use, false test data in § 1.132 declaration)
Misrepresenting the scope of the prior art

Doctrine of Infectious Unenforceability. If inequitable conduct is found in one patent, it may render related patents in the same family unenforceable — the 'infection' can spread through continuation relationships.