What Constitutes a “Public Disclosure” in a Patent Claim?

Under the USA patent law, a person may publicly disclose their invention or offer it for sale prior to filing a patent application, provided that the patent application is filed within 1 year from the date of that first public disclosure or offer for sale. If more than one year has lapsed since the date of first public disclosure or offer for sale, that person can no longer apply for a patent for the invention.

Most countries outside of the United States of America do not have the 1-year grace period. In Europe, for example, a patent claim must be filed earlier the first public disclosure; otherwise, the inventor cannot apply for a patent for the invention as explained on

So what does “public disclosure” mean? What if you told your friend about your invention over dinner one night? Does that count as a public disclosure?

Generally, most countries other than the United States consider any written or oral disclosure, even to a single person, as a public disclosure, unless the recipient of the information agrees to keep the invention in confidence (i.e., by signing a nondisclosure/confidentiality agreement). This means that things such as public lectures, seminars, letters, emails, postings and even conversations can be considered a public disclosure.

In the America, public disclosure must be in writing. This means that written handouts or slides at private meetings, private emails with a business partner or a friend, advertisements, or even academic research papers can be considered a public disclosure, provided that the written disclosure teaches how to make, operate, or duplicate the invention.

In other words, the written disclosure must enable someone how to practice the invention. Merely telling another person that your invention is better than what is already in the market or describing the benefits of your invention, without describing how the invention actually works, is not a public disclosure as you can see from post.

The most prudent thing to do if you are considering applying for a patent is to keep your invention in confidence. If you must discuss with a third-party, be sure to insist on having that third-party sign a nondisclosure agreement to keep your invention in confidence prior to having the discussion.