Duration under English law
Market durations vary by sector - roughly two to five years for technology and SaaS, one to five years (with trade secrets indefinite) for M&A, five to ten or more years for pharma, and the employment term plus one to three years afterwards. But under English law, perpetual confidentiality obligations are generally enforceable, particularly for trade secrets, and the courts have not generally treated a perpetual B2B commercial confidentiality obligation as an unreasonable restraint.
There is a paradox here: a time-limited NDA can provide less protection than equity alone, because once the contractual period expires there is no contractual bar on using the information - whereas the equitable duty might protect it for as long as it stays secret. So a short fixed term can inadvertently cut off protection that equity would have continued.
The US position and the catch-22
US law is different and less forgiving of indefinite NDAs. US courts have struck down indefinite confidentiality obligations covering all information about a business as overbroad, and an over-broad definition can be treated as a de facto non-compete (Brown v TGS Management, California 2020). Yet US trade-secret practice also warns that a time-limited NDA can destroy trade-secret status when the term expires - because the information is then no longer subject to the reasonable steps the statute requires.
That is a genuine catch-22: indefinite all-encompassing NDAs risk being struck down, while time-limited ones risk ending trade-secret protection. The way through is to separate the two kinds of obligation rather than apply one duration to everything.
The bifurcated approach
The solution is a bifurcated duration. For information that constitutes a trade secret, the obligation continues for as long as the information remains a trade secret (indefinitely). For all other confidential information, the obligation runs for a fixed period - commonly three to five years - from disclosure or termination.
This satisfies English law's tolerance for perpetual trade-secret obligations and the US concern about unreasonable indefinite restraints at the same time, and it avoids the trap of a single time limit undermining trade-secret status. Make clear, too, which clauses (non-use, return, remedies, governing law) survive termination.
Cross-border enforcement
Enforcement depends on where you need it. Within Europe, post-Brexit enforcement of English judgments has been substantially restored: the Hague Judgments Convention 2019 came into force for the UK on 1 July 2025 (covering monetary and non-monetary judgments, for proceedings begun on or after that date), and the Hague Convention on Choice of Court Agreements 2005 covers exclusive jurisdiction clauses - so between them, English judgments are enforceable across the standard clause types in contracting states.
Enforcement in the United States is harder: the US is not party to any treaty on recognition of foreign judgments, state regimes cover only money judgments, and foreign injunctions are not enforceable - a fresh US action is needed. So for NDAs with US counterparties, international arbitration deserves serious thought: arbitral awards are far more widely enforceable under the New York Convention, and the clause should expressly empower the tribunal to grant injunctive and provisional relief.
Interim relief and limitation
Two practical wrinkles. Interim injunctions are excluded from the Hague 2019 Convention, so emergency relief must be sought locally in each jurisdiction where it is needed - build that into the enforcement plan. And limitation periods and injunction standards differ across jurisdictions (for example, six years in England, shorter elsewhere; American Cyanamid in England versus likelihood-of-success-plus-irreparable-harm in the US).
So decide, at the drafting stage, the governing law, the forum, and whether to arbitrate - and remember that the speed of emergency relief, which is what confidentiality cases usually need, is a local question wherever the breach happens.
Use at the desk
Practical checklist
- Use a bifurcated duration: indefinite for trade secrets, a fixed term (3-5 years) for other confidential information.
- Do not over-shorten the term - a time-limited NDA can protect less than the equitable duty.
- For US-facing NDAs, avoid indefinite all-encompassing definitions (de facto non-compete risk - Brown v TGS, California 2020).
- Specify which clauses survive termination (non-use, return, remedies, governing law).
- For EU enforcement, rely on Hague 2019 (UK, 1 July 2025) and Hague 2005; for the US, use arbitration (New York Convention).
- Plan for emergency interim relief locally - it is excluded from Hague 2019 - and note differing limitation periods.
This guide is informational only and is not legal advice. It does not replace advice from licensed counsel on the facts of a specific transaction.
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