Many businesses keep a process or formula secret instead of patenting it. The risk is that someone else later patents the same thing. Prior user rights can let you keep using it. In the US, 35 U.S.C. § 273 gives a defence if you used the subject matter commercially in the US, in good faith, at least one year before the patent’s effective filing date or a qualifying public disclosure, and you must prove it by clear and convincing evidence. The UK and Germany have similar rights with different tests. All of them turn on dates, so the time to build your evidence is now, while you are using the process, not after a patent appears. This is general information, not legal advice.
Table of Contents
United States: 35 U.S.C. § 273
The defence in 35 U.S.C. § 273 applies to a process, or to a machine, manufacture or composition of matter used in a manufacturing or other commercial process. You need to show that:
- you acted in good faith and commercially used the subject matter in the United States, either internally or in an arm’s-length sale or transfer of a useful end result; and
- that use happened at least one year before the earlier of the patent’s effective filing date, or the date the invention was publicly disclosed in a way that qualifies for the grace-period exception in 35 U.S.C. § 102(b).
Other points that matter for your records:
- Burden of proof. You must establish the defence by “clear and convincing evidence”, a higher standard than in most civil claims.
- It’s personal. Only the person who did the commercial use, or a related entity, can rely on it. It can’t be licensed, and it can be transferred only with the whole business or line of business it relates to.
- It’s narrow. It covers the specific subject matter you used, plus changes in volume and some improvements, not the whole patent.
- Stopping can lose it. If you abandon the use, you can’t rely on activity before that date for later acts.
- Derivation bars it. You can’t rely on it if you got the subject matter from the patentee.
- Bluffing is costly. If you plead the defence without a reasonable basis and lose, the court must treat the case as exceptional for awarding attorney fees.
United Kingdom: section 64 of the Patents Act 1977
Under section 64, a person who, in the UK and before the invention’s priority date, did in good faith an act that would infringe the patent, or made “effective and serious preparations” to do it, may continue to do that act. The right can’t be licensed to others, but if it arose in a business it can pass with the relevant part of that business. The key date is the priority date, and serious preparations can count, not just actual use.
Germany: section 12 of the Patent Act
Under § 12 PatG, the patent has no effect against a person who, at the time of the application, was already using the invention in Germany or had made the necessary arrangements to do so. That person may use it for the needs of their own business, and the right can only be inherited or sold together with the business.
Other European countries have their own rules, and the effect is national: a prior-use right in one country doesn’t automatically protect you in another.
The records to keep
Every one of these tests asks the same question: what were you doing, where, and by what date? Records made at the time are far more convincing than recollections assembled after a patent appears. Keep:
- The process itself. Procedures, recipes, formulations, parameters, drawings and code, with each version kept rather than overwritten.
- Evidence of commercial use. Production logs, batch records, purchase orders, invoices and delivery records that show the process was in use, not just planned.
- Evidence of preparations. For the UK and Germany, equipment orders, supplier contracts, trial runs and internal approvals.
- Location. Records that show where the use happened, because each of these rights is tied to one country.
- Continuity. Regular records over time, so you can show you didn’t stop and restart.
- Independent dates. A dated record of key documents that doesn’t depend on your own systems’ clocks or on file dates that can be changed. See can a file’s “date created” be changed?
Our page on trade secret records timestamping explains how to date confidential documents without revealing them.
Where a timestamp fits
TimeBinder® records the fingerprint of a document on the Bitcoin blockchain. The fingerprint is made in your browser and the document stays on your device, so a confidential process isn’t disclosed. A TimeBind shows that the exact document existed no later than the recorded time and still matches its fingerprint.
Be clear about the limit. A timestamp dates a document. It doesn’t show that the process was in commercial use, where it was used, or that you invented it. Pair timestamped process documents with your operational records. For the wider choice between patenting, publishing and keeping secret, see defensive publication vs a timestamp, provisional patent vs a timestamp and timestamping invention records.
Frequently Asked Questions
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What are prior user rights?
They are rights or defences that let someone who was already using an invention, or in some countries preparing to use it, carry on after someone else patents it. The details differ by country.
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How long before the patent must I have used the process in the US?
Under 35 U.S.C. § 273, the commercial use must have happened at least one year before the earlier of the patent’s effective filing date or a public disclosure that qualifies for the grace-period exception.
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Can I sell or license my prior user right?
In the US it can’t be licensed, and it can be transferred only as part of the whole business or line of business it relates to. The UK and Germany have similar limits.
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Does a timestamp prove prior commercial use?
No. It proves a document existed by a certain time. You also need records showing the process was actually used commercially, where, and without a break.
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Should I patent my process instead?
It depends on the process, the market and how easily others could find it. Many businesses use a mix of patents, trade secrets and publication. Talk to a patent attorney about your situation.
Date your process documents now
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