What Is a Non-Disclosure Agreement?
A non-disclosure agreement (NDA) is a contract that requires one or both parties to keep certain information confidential. It is one of the most commonly used legal documents in business.
Key Takeaways
- An NDA creates a legal obligation to keep defined information confidential.
- Mutual NDAs protect both parties; unilateral NDAs protect only the disclosing party.
- An NDA only protects information that is genuinely confidential and properly marked or communicated as such.
- NDAs are widely used but are most valuable when backed by proper internal confidentiality practices.
What an NDA is and when to use one
A non-disclosure agreement (NDA), also called a confidentiality agreement, is a contract in which one or both parties agree not to disclose certain information to third parties without authorisation. NDAs are used whenever you need to share sensitive business information — business plans, financial data, product designs, customer lists, technical know-how — with someone outside your organisation, before any formal business relationship is in place. Common scenarios include discussions with potential investors, negotiations with suppliers or partners, early conversations with prospective hires, and engaging consultants who will see your internal data. An NDA creates a legal remedy if the other party misuses or discloses your confidential information.
Mutual vs unilateral NDAs
An NDA can be mutual (bilateral) or unilateral. A mutual NDA protects both parties equally — both sides are restricted from disclosing each other's confidential information. This is the appropriate structure when both parties will be sharing sensitive information, for example in a potential merger or partnership discussion. A unilateral NDA only protects the disclosing party and is appropriate when only one side is sharing sensitive information — for example, if you are sharing your business plan with a potential investor but they are not sharing anything confidential with you. Many investors and large corporates have standard NDA templates; it is reasonable to ask for a copy before you share anything sensitive and to have it reviewed before you sign.
What an NDA actually protects
An NDA is only as useful as the definition of confidential information it contains. A well-drafted NDA will define confidential information broadly but clearly, specify any exclusions (information that is already publicly known, independently developed, or received from a third party without restriction), state the duration of the obligation (typically two to five years, or indefinitely for trade secrets), and specify what happens to confidential materials on termination (return or destruction). Critically, an NDA only protects information that you actually treat as confidential — sharing information carelessly or publicly before the NDA is signed may mean it loses protected status. An NDA is not a substitute for good internal information security practices.
Limitations and enforceability
NDAs are widely used but have real limitations. They do not prevent breaches — they create a remedy after a breach occurs. Enforcing an NDA requires you to demonstrate that confidential information was disclosed, that it was genuinely confidential, and that the other party was the source of the disclosure. This can be difficult and expensive to prove. Courts in England and Wales will enforce reasonable NDAs but will not enforce provisions that are unreasonably broad, such as obligations that amount to a restraint of trade. NDAs also cannot prevent a person from reporting wrongdoing to a regulator — whistleblower protections in UK law override confidentiality obligations in those circumstances. Use NDAs as one layer of protection, not the only one.