An NDA, or nondisclosure agreement, is a contract in which one or both parties promise not to disclose or misuse information the other defines as confidential. The useful way to understand it is that an NDA does two separate legal jobs: it creates a contractual duty of confidence you can sue on directly, and it supplies evidence that you took reasonable measures to keep the information secret, which is a required element of trade secret status.
Those two jobs are worth separating because they fail in different ways. A perfectly drafted contract can still leave you with no trade secret if you handed the material to fifty vendors who never signed anything. And a rigorous secrecy program can still leave you with no contract claim against the one recipient you never papered.
Trade secret law already protects information acquired through a breach of confidence. Under the Defend Trade Secrets Act, misappropriation includes disclosure by someone who knew or had reason to know they owed a duty to maintain secrecy, at 18 U.S.C. § 1839(5). Nothing in that language requires a signature.
Duties of confidence can be implied. The classic authority is Smith v. Dravo Corp., 203 F.2d 369 (7th Cir. 1953), where a company shared shipping container designs during acquisition negotiations that went nowhere, and the buyer built the containers itself. There was no NDA. The Seventh Circuit found a confidential relationship anyway, reasoning that the disclosure was made for a limited purpose and the recipient understood it. Employment, joint ventures, and deal diligence all commonly generate implied duties on similar reasoning.
So why sign anything? Because an implied duty is a fact question you argue to a jury three years and several hundred thousand dollars later. A written NDA moves that question out of the disputed-facts column and into the four corners of a document. It also fixes the scope of the permitted purpose, the survival period, and the remedies, none of which an implied duty gives you.
The second job matters just as much. Trade secret status under § 1839(3) requires that the owner “has taken reasonable measures to keep such information secret.” Executed NDAs are the single most common piece of evidence offered on that element. Courts routinely note the presence or absence of confidentiality agreements when deciding whether reasonable measures existed. An NDA you never sent is a gap in your own proof.
A unilateral NDA binds one side: one party discloses, the other receives and stays quiet. A mutual NDA binds both because both expect to disclose.
The choice tracks the actual information flow, and getting it wrong is expensive in a specific way. If you sign the other side’s unilateral NDA and then talk freely in the meeting, your own disclosures are unprotected by the contract. Worse, a one-way agreement drafted by a sophisticated discloser often contains a residuals clause or a broad license-back that operates only against you. Read who the “Receiving Party” is before you assume the form is neutral.
Two provisions carry most of the weight in any NDA: what counts as confidential, and what does not.
Definitions run along a spectrum. A narrow definition lists specific categories and requires marking, which is clean but fails the moment someone forgets to stamp a file or says something out loud. A broad definition captures anything disclosed in connection with the purpose, which is safer for the discloser but starts to look unreasonable to a court and can create real compliance problems for a recipient with an existing business.
The four standard carve-outs are near universal because they are near unavoidable:
These carve-outs are not concessions to be negotiated away. They mirror what trade secret law already says: information that is generally known or readily ascertainable is not a trade secret at all, and independent development and reverse engineering are lawful means of acquisition, not misappropriation.
Then there is the residuals clause, which permits the recipient’s people to use whatever they retain in unaided memory. Recipients love it. It is common in tech and in venture diligence. Understand what it is: a carve-out broad enough, in an aggressive form, to swallow the agreement, because the most valuable thing anyone takes from a meeting is usually what they remember.
This is the error that quietly does the most damage. Someone sets the confidentiality obligation to expire in three or five years, because that is what the template said.
Trade secrets have no term. They last as long as the information stays secret and derives value from that secrecy. Coca-Cola’s formula is more than a century old. When your NDA’s obligation expires, the contractual duty ends, and the recipient has a serious argument that it is now free to use what it learned. You have taken something potentially perpetual and given it an expiration date, in writing, in your own document.
The standard fix is a bifurcated term: ordinary confidential information stays protected for a defined period, and information qualifying as a trade secret stays protected for as long as it qualifies under applicable law. Note the wrinkle in the other direction. Some states, New York among them, have found perpetual obligations on ordinary business information unreasonable, which is exactly why the bifurcation exists rather than a flat “forever.”
Under 18 U.S.C. § 1833(b), an individual cannot be held liable under federal or state trade secret law for confidentially disclosing a trade secret to a government official or an attorney solely to report a suspected legal violation, or in a sealed court filing.
The part people miss is § 1833(b)(3). An employer must provide notice of that immunity in any contract or agreement with an employee, contractor, or consultant that governs the use of trade secrets or confidential information. The consequence of omitting it is precise: the employer may not recover exemplary damages or attorney’s fees under the DTSA against that employee, even in a case it otherwise wins. Two of the statute’s best remedies, forfeited by a missing paragraph. The notice may be given by cross-reference to a policy document.
Confidentiality provisions drafted broadly enough stop functioning as confidentiality provisions and start functioning as restraints on employment. Courts have noticed.
Brown v. TGS Management Co., 57 Cal. App. 5th 303 (2020), is the cleanest illustration. The confidentiality definition was so sweeping that it reached publicly available information and general knowledge of securities trading, effectively barring the former employee from working in his field at all. The California Court of Appeal held the provisions void as a de facto non-compete under Business and Professions Code § 16600, which voids contracts restraining anyone from engaging in a lawful profession.
The lesson generalizes past California. A confidentiality clause that cannot be complied with except by leaving the industry is a restraint on trade wearing a costume, and drafting it that way risks the clause being struck rather than narrowed.
What is an NDA confidentiality agreement? It is a contract in which one or both parties promise not to disclose or misuse defined confidential information. It does two legal jobs at once. It creates a private duty of confidence enforceable as a breach of contract, and it serves as evidence that the disclosing party took reasonable measures to keep the information secret, which is an element of trade secret protection under 18 U.S.C. § 1839(3).
What is the difference between a mutual and a unilateral NDA? A unilateral NDA runs one way: one side discloses and the other side is bound. A mutual NDA binds both sides because both expect to disclose. The choice is not just etiquette. A unilateral NDA drafted by the discloser tends to be aggressive, and signing it when you will also be sharing your own material leaves your disclosures unprotected and may expose you to a contamination claim.
Do I need an NDA to have a trade secret? No. A duty of confidence can be implied from the relationship and the circumstances, as in Smith v. Dravo Corp., where the Seventh Circuit found a confidential relationship from negotiations alone with no written agreement. But implied duties are litigated facts, not documents. A signed NDA converts a fact question into a written promise and supplies the reasonable-measures evidence courts look for.
Can an NDA last forever? The confidentiality obligation can, and for trade secrets it generally should. A fixed term such as three or five years is a common and costly drafting error, because when the term expires the contractual duty ends and the recipient can argue the information is free to use. That converts a potentially perpetual trade secret into a time-limited one. A common fix is a term that runs for a set period for ordinary confidential information and for as long as the material qualifies as a trade secret under applicable law.
Going further: How to write an NDA that holds up .
This page is general legal information, not legal advice, and it does not create an attorney-client relationship.
The Federal Circuit upheld a $57.6M NDA-breach verdict even though the underlying patent was invalid as anticipated, showing contracts can beat patents.
A 1959 court held Listerine's maker owed royalties on an 1881 secret-formula contract even after the formula went public, because the contract set duration.
The First Circuit voided a tax firm's nondisclosure agreement as too sweeping and tossed its trade-secret verdict, holding that an NDA that bars general knowledge functions like an illegal noncompete.
The SEC's largest stand-alone Rule 21F-17(a) settlement turned a routine settlement-release clause into an enforcement event, showing that NDAs are now read for what they silence, not just what they protect.
A California appellate court voided an employer's sweeping confidentiality provisions as a de facto noncompete that barred a trader from his profession for life.
The Ninth Circuit held that a proviso unambiguously ended an NDA's confidentiality obligations after two years, vacating a $60 million verdict because the jury never heard that defense.
The Federal Circuit held that a disclosing party who ignored its NDA's written-designation protocol lost trade-secret protection at the moment of disclosure.
