Patent Strategy

Validity Opinion

A validity opinion assesses whether an issued patent is likely invalid — informing IPR petition strategy, litigation defense, and negotiating leverage against a licensing demand.

What is a validity opinion and when is it needed?

A validity opinion (often called an invalidity opinion or patent validity analysis) is a formal written analysis by a patent attorney assessing the likelihood that a specific patent will be found invalid in litigation or post-grant proceedings.

Purpose. To evaluate the strength of a patent's validity before making business decisions that depend on whether the patent can be enforced

When Obtained

(1) Litigation Preparation. Before filing an IPR petition, understanding which invalidity grounds are strongest

(2) Acquisition Due Diligence. When acquiring a patent portfolio, assessing the validity of key patents

(3) Licensing Response. When threatened with a license demand, assessing whether the patent is likely invalid (which affects negotiating leverage)

(4) Product Launch. Combined with a non-infringement opinion — if the product infringes, can the patent be attacked as invalid?

(5) Settlement Evaluation. In pending litigation, evaluating the probability of success on invalidity claims

Contents of a Validity Opinion

(a) identification of the patent being analyzed
(b) claim construction for each claim
(c) prior art search and analysis under § 102 (anticipation)
(d) obviousness analysis under § 103 (prior art combinations)
(e) § 101 subject matter eligibility analysis (if relevant)
(f) § 112 written description, enablement, and indefiniteness analysis
(g) conclusion: patent is likely valid / likely invalid / validity is unclear

Distinguished from Infringement Opinion

Infringement opinion asks 'does our product infringe the patent?'
Validity opinion asks 'is the patent valid?'
Both can be needed simultaneously.

What prior art grounds does a validity opinion analyze?

A validity opinion examines multiple bases for patent invalidity: § 102 ANTICIPATION: the most straightforward invalidity ground; a single prior art reference that discloses every element of a claim (expressly or inherently) anticipates the claim; validity opinion identifies: (a) prior patents and publications filed/published before the effective filing date; (b) prior public use, sales, or other disclosures; (c) analyzes whether any single reference discloses all claim elements;.

Search Strategy

Validity searches are MORE EXTENSIVE than patentability searches (conducted before filing) because: (a) the claims are now known — the search is focused on what the claims actually cover
(b) the searcher looks for the 'best' prior art, not just any art
(c) prior art categories are broader (use, sale, foreign public knowledge count under AIA § 102(a)(1))
§ 103 OBVIOUSNESS: the most common invalidity basis in validity opinions
Often requires combining two or more prior art references
Analyzes: (a) the primary reference (closest to the claim)
(b) the secondary reference (teaching the missing element)
(c) motivation to combine (would a skilled artisan have been motivated?)
(d) secondary considerations (commercial success, long-felt need, failure of others)
KSR INTERNATIONAL v. TELEFLEX (S.Ct. 2007): expanded obviousness analysis — 'obvious to try' can establish invalidity
Combinations of known elements can be obvious even without specific teaching to combine
§ 101 SUBJECT MATTER ELIGIBILITY: for software, business methods, and diagnostic claims
Alice/Mayo two-step analysis
Useful when the patent involves abstract ideas or natural phenomena
§ 112 GROUNDS: written description (claims not supported by the specification)
Enablement (skilled artisan could not make and use the full claim scope — Amgen v. Sanofi, S.Ct. 2023)
Indefiniteness (claims not reasonably certain — Nautilus, S.Ct. 2014).

How does a validity opinion interact with willful infringement and attorney-client privilege?

The privilege and willfulness implications of validity opinions are similar to but distinct from infringement opinions.

Attorney-client Privilege

A validity opinion authored by a patent attorney within the attorney-client relationship is privileged
The client can keep it confidential
It cannot be discovered by the opposing party unless the client waives privilege

Waiver by Assertion. If a defendant invokes a validity opinion as evidence in litigation (e.g., to show good-faith reliance on an invalidity argument), privilege is waived for the opinion and related communications

Willful Infringement Interaction

After Halo Electronics v. Pulse Electronics (S.Ct. 2016), willful infringement is assessed based on subjective bad faith — did the infringer deliberately copy the patent knowing it was valid?
A validity opinion can establish a good-faith belief that the patent is invalid
A defendant who relies on a validity opinion showing likely invalidity has a defense against willfulness even if the court ultimately finds the patent valid
COMBINED INFRINGEMENT + VALIDITY OPINION: the most common approach is to obtain both: (a) non-infringement opinion: our product doesn't infringe because element X is missing
(b) validity opinion: even if we infringe, the patent is likely invalid for prior art Y
This provides dual protection against enhanced damages
IN-HOUSE vs.

Outside Counsel. The same considerations as infringement opinions apply — outside counsel opinions typically receive more deference from courts

Opinion Timing

A validity opinion obtained AFTER receipt of a cease-and-desist letter helps establish good-faith reliance going forward
It does not retroactively excuse pre-opinion infringement.

How is a validity opinion used in connection with IPR petitions?

Validity opinions are closely related to IPR petition strategy, though they serve different purposes.

Validity Opinion as IPR Roadmap

A thorough validity opinion identifies the strongest prior art grounds and maps them to specific claims
This directly informs which claims to challenge in an IPR and which prior art references to use

Differences Between a Validity Opinion and an IPR Petition

Validity opinion: comprehensive private analysis
Assesses all grounds (§ 101, § 102, § 103, § 112)
Focused on identifying the best grounds
Not limited to patents and printed publications
IPR petition: public filing at PTAB
Limited to § 102 and § 103 grounds based on patents and printed publications only
Must meet the 'reasonable likelihood of success' threshold for institution
Subject to § 315(e) estoppel if FWD is issued

Timing

Validity opinion should be completed BEFORE filing the IPR petition
The opinion identifies which arguments are strong enough to include in the petition
Including weak grounds in an IPR can jeopardize the overall petition

Estoppel Caution

An IPR petition creates § 315(e) estoppel for all grounds raised AND grounds reasonably could have been raised
The validity opinion helps identify which prior art grounds to EXCLUDE from the IPR (preserving them for trial litigation on grounds not raised in IPR, or on non-patent art)

Grounds not Available in IPR

§ 101 and § 112 grounds cannot be raised in IPR
The validity opinion may identify § 101 or § 112 as stronger grounds — these should be preserved for district court litigation and cannot be raised in IPR.

What is the difference between a validity opinion and a patentability opinion?

These opinions analyze patent validity from opposite ends of the process.

Validity Opinion (Post-grant)

Conducted AFTER a patent has issued
Assesses whether the issued patent is valid based on issued claims and the full prosecution history
Uses the Philips claim construction standard (how a court would interpret the claims)
Analyzes whether issued claims survive § 101, § 102, § 103, and § 112 challenges
The audience is a defendant in litigation or an IPR petitioner

Patentability Opinion (Pre-grant)

Conducted BEFORE filing a patent application or during prosecution
Assesses whether the claimed invention is likely patentable (non-obvious, novel) over the prior art
Uses the broadest reasonable interpretation (BRI) claim construction standard applied during examination
Advises the applicant whether to proceed with filing and how to draft claims
The audience is a patent applicant
INVALIDITY SEARCH vs.

Patentability Search

Both involve prior art searches, but with different objectives
Patentability search: find any art that might prevent patenting
Invalidity search: find the BEST art most likely to invalidate specific claims
Invalidity searches are typically more targeted and thorough than initial patentability searches

Patent Acquisition Due Diligence

When acquiring a patent portfolio, a validity opinion is essential for key patents
The opinion assesses whether the patents can withstand IPR challenges or invalidity defenses in litigation
Patents that appear valid are more valuable
Patents that are likely invalid have reduced value and may be liabilities if enforcement is attempted.