A filing date is the one date in the whole process nobody argues about. It sits on a public register, entered by a party with no interest in the outcome. Every other date around a patent is held in private files, and those are the dates that get fought over.
When the invention was conceived. What you had at that point. Who you showed it to, and in what form. Whether anything reached the public first. None of it is on any register, and none of it is easy to prove from records you produced yourself.
| Date | Who records it | If it is contested |
|---|---|---|
| Filing and priority date | The patent office, on a public register | It is not contested. This one is settled |
| When the invention was conceived | Nobody. Your own notebooks and files | Your records against theirs, both self-produced |
| What you showed under NDA, and to whom | Each party separately | Competing accounts, and a sent folder proves little |
| Whether anything was public before filing | Nobody, until someone goes looking | Reconstructed years later from whatever survives |
| Prior commercial use before a rival filing | Your own business records | In the US, must be proved by clear and convincing evidence |
Only the first row is settled by an independent party. Everything below it is your word, supported by files on machines you control, against somebody with the opposite interest.
If somebody patents what you were already doing, you are not necessarily finished. Section 64 of the Patents Act 1977 gives a person who, in the United Kingdom before the priority date, in good faith did an act that would have infringed the patent, or made in good faith effective and serious preparations to do one, the right to carry on despite the grant. The right does not extend to licensing anyone else to do the act. The leading authority is Lubrizol Corporation v Esso Petroleum Co Ltd [1998] RPC 727.
The United States has a narrower equivalent in 35 U.S.C. 273. It is confined to subject matter consisting of a process, or a machine, manufacture or composition of matter used in a manufacturing or other commercial process, and it requires good faith commercial use in the United States at least one year before the earlier of the effective filing date or a public disclosure qualifying for the section 102(b) exception. It has to be pleaded, and courts have struck it out when raised too late. It also has to be established by clear and convincing evidence, a higher standard than the ordinary civil balance.
The two differ in scope and in the standard of proof, and they are made of the same material. Not novelty, not inventiveness, not the merits of anyone's patent. Purely what you were doing and when you were doing it. A defence built entirely out of dates survives or fails on the quality of the dated evidence, and in the United States that evidence has to reach clear and convincing, which is demanding to meet with internal documents alone.
Under the European Patent Convention the state of the art is everything made available to the public before the filing date, and there is no general grace period. The exceptions in Article 55 are narrow, covering evident abuse in relation to the applicant and display at an official or officially recognised international exhibition, and only where the disclosure occurred no earlier than six months before the actual filing of the European application. The Enlarged Board settled in G 3/98 and G 2/99 that the six months runs from the filing date, not the priority date. A talk, a paper, a public repository or a trade show demonstration before filing can end the possibility of a European patent.
The United States is more forgiving and still evidential. A disclosure made a year or less before the effective filing date is not prior art against the inventor where it came from the inventor, or from someone who obtained it from them. Relying on that means proving the disclosure was yours and establishing when it happened, which is the same evidence problem in a friendlier setting.
Both point at the same discipline. Record the position before you disclose anything, so that whatever happens afterwards can be placed against a fixed point rather than reconstructed from calendars, invoices and recollection. Where the invention is software, our post on software prior art goes further into the patent side. Where disclosure is the deliberate strategy rather than a risk to manage, see defensive publication.
One automated sequence, each step taking the output of the one before it. The file is hashed with SHA-256. That hash is timestamped under RFC 3161 by an accredited trust service provider. The timestamped hash is anchored to the Bitcoin blockchain through OpenTimestamps. Only the hash travels, so the invention stays confidential, which matters more here than anywhere: recording it must not itself be a disclosure.
eIDAS qualification is a separate option on top of that sequence. With it, the timestamp carries the presumption under Article 41(2) that the date and time are accurate and the data intact, which shifts the burden to the party disputing it. A blockchain anchor on its own does not carry that presumption, a distinction set out in blockchain timestamps compared with qualified timestamps.
Every certificate can be checked without us, using SHA-256, OpenSSL, the European Commission's trusted lists and any OpenTimestamps client, which matters in a dispute where the other side has no reason to take our word for anything. Our timestamp validator is open source and checks any provider's timestamp, not only ours.
Where the invention is shown to investors, partners or manufacturers before filing, sharing from a vault records each recipient and each view against a timestamp, and each recipient can be issued an individually watermarked copy. The scope of what an agreement covers is a separate question, taken up on NDAs and contracts.
Record your first deposit →It proves when you filed. The office records the filing date and the priority date, and those are settled facts on a public register that nobody needs to evidence separately. What the office does not record is when the invention was conceived, what you had at that point, who you showed it to before filing, or whether anything about it reached the public first. Those questions are answered from your own files, and in a dispute your own files are the weakest evidence available because you produced and control them.
Because the filing race is not the only fight. Under the America Invents Act a derivation proceeding turns on whether the earlier applicant took the invention from you, which is a question about what you had and when. Inventorship disputes, ownership arguments with employers or contractors, and reliance on the grace period for your own earlier disclosure all rest on the same evidence. First-inventor-to-file settled who gets the patent when two people file. It did not remove the need to show what you had before you filed.
Section 64 of the Patents Act 1977 gives a person who, in the United Kingdom before the priority date of a patent, in good faith did an act that would have infringed it, or made in good faith effective and serious preparations to do such an act, the right to carry on doing it despite the grant. The right does not extend to licensing anyone else to do it. The leading authority is Lubrizol Corporation v Esso Petroleum Co Ltd [1998] RPC 727. The defence is entirely about what you were doing and when, so it stands or falls on dated evidence.
A defence to infringement under 35 U.S.C. 273, as amended by the America Invents Act. It is narrower than the UK equivalent. It applies to subject matter consisting of a process, or a machine, manufacture or composition of matter used in a manufacturing or other commercial process. It requires good faith commercial use in the United States, and that use must have occurred at least one year before the earlier of the effective filing date of the claimed invention or a public disclosure qualifying for the exception under section 102(b). It has to be pleaded, and courts have struck it when raised late. It has to be established by clear and convincing evidence, which is difficult to reach with internal records alone. There are further conditions, including on nonprofit and regulatory-review situations, so this is one to put to US patent counsel.
It depends where you want protection, and the answer is unforgiving in Europe. Under the European Patent Convention the state of the art is everything made available to the public before the filing date, and there is no general grace period. The exceptions in Article 55 are narrow, covering evident abuse in relation to the applicant and display at an official or officially recognised international exhibition, and only where the disclosure occurred no earlier than six months before the actual filing of the European application. G 3/98 and G 2/99 confirmed that the six months runs from the filing date rather than the priority date. In the United States the position is different: a disclosure made a year or less before the effective filing date is not prior art against the inventor if it came from the inventor or from someone who obtained it from them. Relying on that exception means proving the disclosure was yours and when it happened.
The invention disclosure itself, at the point it is written up rather than at the point of filing. Alongside it, the material a dispute would reach for: design documents, test results, drawings, specifications, the version of a prototype description that existed at a given moment. Then each version as the work develops, so the sequence shows how the invention took shape. A single record proves one moment. A sequence shows a progression, which is what distinguishes someone who developed a thing from someone who arrived at it later.
Under an agreement, and from somewhere that records what was shown to whom. A disclosure made in confidence does not make the invention available to the public, so it does not destroy novelty, but the evidential position matters if the material later surfaces elsewhere. Sharing from an access-controlled vault logs each recipient and each view against a timestamp, and individually watermarked copies mean a leaked document identifies who received it. The scope of what an agreement covers is a separate question, dealt with on our NDAs and contracts page.
It depends on where the dispute is heard. In the EU a qualified electronic timestamp carries a presumption under Article 41(2) of Regulation 910/2014 that the date and time are accurate and the data intact. The presumption is rebuttable, shifting the burden to the party disputing it. It applies across all EU member states, and the EEA states recognise qualified timestamps through the EEA Agreement. The UK retains an equivalent framework including the presumption, and recognition between the two regimes now runs one way: UK law continues to recognise EU qualified trust service providers, while the EU no longer recognises UK-registered ones. The United States has no equivalent statutory presumption, so the record is assessed under ordinary rules of evidence.
This page gives general information about evidence around patent filings. It is not legal advice, and nothing here is a recommendation about whether or when to file. For a specific matter, consult a qualified patent attorney in the relevant jurisdiction.