What evidence should I preserve to support prior-use rights if someone else later patents the technology?

Record the technology and what the business actually did

Prior-use rights may allow a business to continue certain activities despite a later patent. The qualifying facts differ between countries, including whether the law recognises actual use, preparations or prior possession of the invention. WIPO’s comparative study explains these differences and the importance of preserving evidence when the activity occurs.

Keep enough technical detail to identify the version involved: drawings, specifications, source code, formulations, machine settings or operating instructions. Link each version to records showing how it was used, such as production logs, batch sheets, installation records, test reports or customer deliveries. A drawing shows a design; it does not alone show that a machine was built or operated.

For example, a manufacturer using a particular mixing method could preserve the operating instructions, equipment settings and batch records identifying the dates, site and operator. Sales or delivery records for the resulting products add commercial context. Together, these documents connect the technical method to identifiable operations.

Distinguish development, preparation and actual use

Keep the stages separate. Laboratory experiments, an approved investment, an equipment order, commissioning and routine production describe different activities. Record what had actually happened at each date, including cancellations or unfinished work.

Where implementation was being prepared, preserve purchase orders, supplier correspondence, site plans, tooling specifications and installation schedules. These help explain the commitment made and how close the business was to using the technology.

The legal threshold needs checking locally. For example, UK law can recognise effective and serious preparations made in good faith before the relevant priority date. The US prior-commercial-use defence generally requires qualifying commercial use at least one year before the earlier of the effective filing date or a public disclosure qualifying for the statutory grace-period exception. Merely showing that work predates the patent’s grant is therefore insufficient.

Identify the business, location and origin of the work

Name the legal entity carrying out the activity and the facility and country where it occurred. If contractors or group companies were involved, retain their instructions, agreements and records of the work performed. Do not assume that activity by one company or in one country automatically establishes rights for another.

Preserve records explaining how the technology was obtained: development notes, earlier designs, contributor correspondence and any relevant licences. These can help address questions about independent development and good faith.

Also record later changes to the technology, production sites and business ownership, and any interruption in use. Their effect on the right depends on local law; retaining them allows an adviser to assess continuity and the scope of the activity that may be protected.

Preserve and timestamp the records as events occur

Build successive collections around meaningful events: a completed trial, equipment commissioning, the start of production or a technical revision. Keep the original production logs, test reports and correspondence. For each, record where it came from—for example, the factory’s production system, the testing laboratory or the equipment supplier. Retain supplier and customer documents alongside internal notes where they corroborate the same events.

Timestamp each collection promptly and retain its exact files, certificates and verification data. Bitcoin anchoring and authority-issued timestamps can support this chronology; see what a digital timestamp establishes. A timestamp dates the preserved material, but does not independently establish that an operation described in it took place.

In the mixing-method example, timestamped collections from trials, commissioning and production help preserve the sequence of technical and operational records. Timestamping only the final operating manual would not establish when the trial or commissioning records existed. Keep confidential material under access controls; collecting this evidence does not require publishing the technology.

Use the records when a later patent becomes relevant

These steps build the evidence an adviser will need. Deciding whether it supports continued operation requires comparing the recorded activity with the patent and the local conditions for prior-use protection. See what freedom to operate means and how prior use affects it for that assessment, including the limits on changed or expanded operations.