Patent Opinion Letters

What is a patent opinion letter?

A patent opinion letter is a formal written legal analysis from patent counsel addressing a specific patent question. The four standard types: (1) Patentability opinion — before filing, assesses whether an invention is likely patentable over located prior art (§§ 102/103); informs the filing decision and claim strategy. (2) Freedom-to-operate (FTO) opinion — before product launch or major investment, searches for in-force third-party patents and pending applications covering the product's technology, analyzes threatening claims against the product, and concludes whether the product is clear or faces specific risks; FTO is jurisdiction-specific (a US FTO opinion says nothing about Europe) and time-limited (pending applications can issue later with new claims). (3) Non-infringement opinion — after a specific patent is identified (typically via a demand letter), provides an element-by-element analysis concluding the product does not infringe the properly construed claims, literally or under the doctrine of equivalents. (4) Invalidity opinion — concludes that asserted claims are invalid over prior art (§ 102 anticipation, § 103 obviousness) or under § 112, acknowledging the clear-and-convincing standard in district court. Functions: managing willfulness exposure (a competent opinion is strong evidence against enhanced damages); informing business decisions (launch, redesign, license, fight); supporting transactions (FTO opinions are sometimes deliverables in financings); and evaluating challenges (invalidity analysis feeds IPR decisions). An opinion letter is legal advice protected by attorney-client privilege until the client chooses to rely on it in litigation — at which point privilege is waived as to the opinion's subject matter, a strategic trade-off made at trial, not when the opinion is written.

How does an opinion of counsel protect against willful infringement?

Enhanced damages under 35 U.S.C. § 284 — up to treble — require conduct that is egregious: willful, wanton, deliberate, or in bad faith (Halo Electronics v. Pulse Electronics, U.S. 2016). The inquiry focuses on the accused infringer's state of mind: did it act despite knowing, or being willfully blind to, an objectively high risk of infringing a valid patent? A competent opinion of counsel attacks this directly: a company that, upon learning of a patent, promptly obtained a thorough written analysis from qualified counsel concluding non-infringement or invalidity — and reasonably relied on it — has powerful evidence that its continued conduct was in good faith rather than reckless. Key legal points: (1) An opinion is evidence, not an absolute defense — courts weigh its competence, timing, and whether reliance was genuine; a transparently superficial opinion bought as 'insurance' can backfire. (2) 35 U.S.C. § 298 (enacted in the America Invents Act) provides that the failure to obtain an opinion, or the failure to present one at trial, may NOT be used to prove willfulness or intent to induce infringement — eliminating the pre-AIA adverse inference that punished companies for not buying opinions. So there is no obligation to obtain one; the calculus is purely about affirmative protection. (3) Timing matters enormously: an opinion obtained promptly after a demand letter protects the sales that follow; an opinion commissioned on the eve of trial protects almost nothing. (4) Reliance must be real: executives must actually receive and consider the opinion; an unread opinion in a drawer shows nothing about state of mind.

What is the privilege waiver problem with relying on an opinion letter?

Opinion letters are attorney-client privileged when written. But to USE an opinion as a willfulness defense at trial, the defendant must disclose it — and disclosure waives privilege as to the subject matter of the opinion, not just the document itself. The scope of the waiver: under In re EchoStar Communications Corp. (Fed. Cir. 2006), advancing an advice-of-counsel defense waives privilege over communications and documents concerning the same subject matter (e.g., infringement of the asserted patent) — including other communications between the client and opinion counsel, and uncommunicated work product that reflects what was conveyed. Critically, In re Seagate Technology (Fed. Cir. 2007, en banc) held that relying on opinion counsel's advice does NOT automatically waive privilege as to TRIAL counsel's communications — the waiver generally stops at opinion counsel, which is a principal reason companies use separate, independent opinion counsel rather than the litigation team. Practical consequences: (1) The decision to rely on the opinion is made during litigation, weighing the opinion's helpfulness against what the waiver exposes — internal emails questioning the opinion's conclusions, drafts showing negotiated language, or candid risk assessments can be devastating. (2) Companies should keep opinion-counsel files clean: separate engagement, separate files, no mixing with strategic litigation communications. (3) Executives' communications about the opinion should be disciplined — a CEO email saying 'legal says we're probably fine but I'm nervous' enters evidence with the waiver. (4) Because of § 298, declining to waive and simply not relying on any opinion carries no adverse inference — the fallback is always available.

What makes a freedom-to-operate opinion different from a patentability opinion?

They answer unrelated questions, and conflating them is one of the most common founder mistakes. Patentability asks: is MY invention new and non-obvious enough to win a patent? It compares your invention against all prior art — including expired patents, ancient publications, and abandoned applications — because anything public before your priority date can defeat novelty. Freedom to operate asks: does MY product infringe anyone else's CURRENTLY ENFORCEABLE patent? It compares your product against in-force (unexpired, fees-paid) patent claims in the jurisdictions where you will make, use, or sell. The independence cuts both ways: (1) You can have a patent and still infringe — your patented improvement on someone's foundational patented technology still requires their license to practice (a patent is a right to exclude, not a right to practice); this is the classic 'blocking patents' situation. (2) You can be free to operate without being able to patent — if your product uses only technology from expired patents, FTO is clear (expired patents are free for all), but those same expired patents are prior art that defeats your patentability. Search scope differs too: patentability searches cast a wide net across all time and all countries; FTO searches focus on unexpired patents and pending applications in specific markets, but must analyze claims with far more care because the legal stakes are infringement liability. This is why FTO opinions cost dramatically more ($10,000–$50,000+) than patentability opinions ($1,500–$5,000): the claim-construction analysis on every threatening patent is lawyer-intensive, and the consequences of error are litigation, not a rejected application.

When should a startup pay for an opinion letter, and when is it overkill?

Opinion letters are expensive, and the honest answer is that most early-stage activity doesn't need one. When an opinion is genuinely warranted: (1) After a demand letter or known specific threat — a non-infringement and/or invalidity opinion both guides the response and caps willfulness exposure for continued sales; this is the clearest use case. (2) Before betting the company on a launch in a dense patent field — medical devices, pharmaceuticals, semiconductors, agricultural biotech, and standardized technologies (wireless, video codecs) are litigation-heavy; an FTO review before committing manufacturing capital is standard practice in these industries and often demanded by investors and acquirers. (3) When an acquirer, investor, or commercial partner requires it — FTO or title opinions sometimes appear as deal deliverables. (4) Before designing around a known patent — counsel sign-off that the redesign clears the claims as construed (including equivalents) is the difference between an actual design-around and an expensive illusion. When it is usually overkill: (1) Pre-launch FTO for a typical software MVP — comprehensive software FTO is close to impossible (claim language is abstract, the field is dense with low-quality patents) and rarely commissioned; the standard posture is responding to specific threats if they materialize. (2) General 'are we safe?' anxiety with no specific patent identified — there is no meaningful opinion without a specific claim set to analyze. (3) Patentability opinions for cheap provisional filings — many startups file a provisional first and let the examiner's search inform strategy. Calibrations between extremes: a counsel 'clearance review' (analysis without a formal signed opinion) costs a fraction of a formal opinion and may suffice for intermediate-risk decisions; and remember § 298 — skipping an opinion cannot be held against you later, so the spend is purely about affirmative protection and decision quality.