← All articles · October 2026 · 6 min read

Defensive Publication: Publish Prior Art Instead of Patenting

If you only need to stop others from patenting your idea, publishing it can be enough. What counts as prior art, where to publish, and what a timestamp adds.

What Is a Defensive Publication?

A defensive publication is a public disclosure of an invention made on purpose so that nobody, including you, can later patent it. Instead of claiming exclusive rights, you put the idea into the public record as prior art. Once it is there, a patent examiner can cite it against any later application that claims the same thing.

Companies have used the technique for decades for inventions they want to keep using freely but do not think are worth the cost of a patent. Open-source projects and researchers use it for the same reason. It is a choice between owning an idea and making sure no one else can own it.

Defensive Publication or Patent?

A patent gives you the right to stop others from making, using or selling your invention, for a limited time and only in the countries where it is granted. It costs money to file, prosecute and maintain, and it takes years.

A defensive publication gives you no exclusive right at all. What it gives you is freedom to operate: if someone later tries to patent the same thing, your publication can be used to block or invalidate that patent. It is usually fast and cheap.

A simple way to decide:

1. You want to license the invention or stop competitors from copying it — talk to a patent attorney about filing.
2. You only want to keep using it without someone else patenting it and charging you — a defensive publication may be enough.
3. You are not sure yet — do not publish. Publishing is irreversible and can destroy your own ability to patent.

What Makes a Publication Count as Prior Art

Prior art is defined by patent law, and a disclosure has to meet that definition to work defensively.

It must be public. In the US, 35 U.S.C. § 102(a)(1) counts an invention that was "described in a printed publication, or in public use, on sale, or otherwise available to the public" before the filing date. Under the European Patent Convention, Article 54 says the state of the art is everything made available to the public before the filing date. A private note, a sealed envelope or a private hash is not available to the public, so it is not prior art.

It must be dated. An examiner or a court needs to know that the disclosure came before the other party's filing date.

It must be specific enough. To anticipate a later claim, a disclosure generally has to describe the invention in enough detail that a skilled person could carry it out. A one-line concept rarely blocks a detailed patent claim. Describe how it works, the variants you can think of, and drawings or examples where they help.

It must be findable. Examiners search patent databases and established technical repositories first. A page buried on a personal site may be valid prior art in theory but never found in practice.

Where to Publish

Common options, from most to least visible to patent examiners:

1. Dedicated prior-art repositories, such as the IP.com Prior Art Database, Research Disclosure, and Technical Disclosure Commons. They exist for this purpose and are indexed by searchers.
2. Scientific and technical publishing: journals, conference papers, and preprint servers such as arXiv for fields they cover.
3. Public code repositories and technical documentation, with dated releases.
4. Your own website or blog. Valid in principle, but the date is easier to dispute and examiners are less likely to find it. Archiving the page with the Internet Archive's Wayback Machine adds an independent dated copy.

In the US, the USPTO used to offer a Statutory Invention Registration for this purpose; it was abolished by the America Invents Act and is no longer available.

The Risk: You Lose Your Own Patent Rights

A defensive publication works against you too. In Europe and most other countries novelty is absolute: once you publish, you generally cannot patent the invention yourself. The US gives inventors a one-year grace period after their own disclosure (35 U.S.C. § 102(b)(1)), but relying on it means you have already lost most foreign rights. If there is any chance you will want a patent, speak to a patent attorney before you publish, not after.

Where a Timestamp Fits — and Where It Does Not

A timestamp is not a defensive publication. icalledit.io writes a SHA-256 hash of your record into its own Bitcoin transaction. The hash reveals nothing about the content, so on its own it puts nothing into the public record and does not count as prior art.

What it can do is support the publication. Websites can be edited and repository entries can be updated. If you timestamp the exact document you publish, you have independent, checkable evidence that this exact text existed no later than that date, without relying on the platform you published on. Together with the public copy, that makes your dates harder to challenge. It is also useful for the drafts you keep private while you decide whether to publish or file.

You get a PDF certificate and a proof.json file, so anyone can verify the record without our website. It proves existence at a time, not authorship, novelty or public availability, and it is not legal advice. One registration costs $19; the preview is free and is not written to Bitcoin.

Frequently Asked Questions

What is a defensive publication?

A deliberate public disclosure of an invention so that it becomes prior art. It does not give you a patent; it prevents others, and you, from patenting the same thing later.

Is a defensive publication cheaper than a patent?

Usually, yes. Publishing on your own site or a preprint server can be free, and dedicated prior-art repositories charge far less than drafting and prosecuting a patent. The trade-off is that you get no exclusive rights.

Does a blockchain timestamp count as prior art?

Not on its own. A timestamp stores a hash, which reveals nothing about the content and is not available to the public. It can support a defensive publication by proving the exact published text existed by a date, but the content itself still has to be published.

Can I still patent an idea after publishing it?

In most countries, no, because novelty is lost when you publish. The US allows a one-year grace period for the inventor's own disclosure, but foreign rights are usually lost. Talk to a patent attorney before publishing if you might want a patent.

How detailed does a defensive publication need to be?

Detailed enough that a skilled person could carry out the invention from it. A short concept description rarely blocks a detailed patent claim; include how it works, variants, and drawings or examples.

A timestamp proves that content existed at a point in time. It is not legal advice, a patent, a trademark or a copyright registration. Compare the options.

Timestamp your idea · See pricing