Prior Art and Defensive Publication
By BlockchainSignPublished
There is a strategy that sounds backwards and is often correct: publish your invention so that nobody, including you, can patent it.
It is worth understanding, partly because it is genuinely useful and partly because it is the case where a private timestamp does not do the job people hope.
What prior art is
Everything publicly available before a filing date that bears on whether an invention is new. If your invention is already in the prior art, it is not novel, and the application fails.
Prior art is not limited to patents. Journal articles, conference papers, product manuals, websites, public demonstrations, theses and forum posts all count, provided they were publicly accessible and describe the invention sufficiently.
What defensive publication does
Defensive publication is deliberately putting an invention into the prior art so that nobody else can obtain a patent on it.
The reasoning is economic. Patents are expensive to obtain and expensive to maintain. For an improvement you want to keep using but do not intend to monetise through licensing, spending tens of thousands to exclude others may make no sense — while the risk of somebody else patenting it and coming after you is real.
Publishing removes that risk for a fraction of the cost. You cannot exclude anyone, and neither can anyone else.
Common venues: technical disclosure journals, arXiv or similar preprint servers, company engineering blogs, conference proceedings, and open source releases with documentation.
The requirement that catches people
To count as prior art, a disclosure must be publicly accessible and must enable someone skilled in the field to practise the invention. Publishing a vague description that does not teach how to do it may not block a later application on the specific implementation.
If defensive publication is the goal, write it as you would write a patent specification: complete, enabling, specific, and dated.
Why a private timestamp is not defensive publication
This is the distinction that matters, and it goes in the opposite direction to most of this site.
A timestamp is private by construction. Only a hash is published. Nobody can read the contents, learn anything from them, or use them. It creates no public disclosure at all — which is exactly what makes it suitable for confidential material, and exactly what makes it useless as prior art.
To defeat someone else's future patent you need the invention to be publicly readable. A hash on a ledger is not.
| Goal | Right tool |
|---|---|
| Stop others patenting it | Defensive publication |
| Keep it secret and prove you had it | Timestamp |
| Exclude others and monetise | Patent |
| Keep it secret and prevent misuse | Trade secret plus NDAs |
The one thing a timestamp adds to defensive publication
The publication is what creates the prior art. What a timestamp can do is fix the date of the document you published, in a way a blog post's own date field cannot.
Publication venues vary in how firmly their dates are established. A journal with an editorial process is solid. A self-hosted post with an editable date is not. Timestamping the document as published gives you an independent anchor on when that exact text existed, alongside the publication that makes it accessible.
Small contribution, occasionally decisive if the publication date is later questioned.
Choosing
Publish defensively if you want to keep using it, do not plan to license it, and the main risk is somebody else patenting it.
File if exclusivity has commercial value that justifies the cost.
Keep it secret if it is not reverse-engineerable from your product and secrecy is sustainable. See how to prove a trade secret without disclosing it.
Timestamp in the last case, and alongside the first. Not instead of either.
General information, not legal advice.