It is my understanding that patents can be invalidated if there is prior art to the technique at hand; DJB has a piece that would suggest that this way authors can inadvertently invalidate their own patents, if not being careful with information disclosure.


Diffie disclosed the idea of public-key cryptography at a conference in June 1976. Diffie and Hellman also distributed preprints of their ``New Directions in Cryptography'' paper, which disclosed the Diffie-Hellman system, at that conference and by mail. For example, Mike Matyas received a copy in August 1976. The patent was filed in September 1977.

Under United States case law, a document has been published if it ``has been disseminated or otherwise made available to the extent that persons interested and ordinarily skilled in the subject matter or art, exercising reasonable diligence, can locate it.'' A patent is automatically invalid if the patented invention was published more than a year before the patent's filing date.

It appears, therefore, that the Diffie-Hellman-Merkle patent was invalid. In the subsequent court case MIT v. Fortia, another patent was invalidated for the same reason: the inventor handed out six copies of a preprint at a conference fourteen months before applying for the patent.

How does this work in the general case? Is it important that in both examples a whole year has passed between the publishing and the patent application?

Is it necessary for a significant amount of time to pass between the publishing of a paper, and the patent application, for the patent to be subsequently declared invalid?

Specifically, if one's university explicitly claims that it has no interest in one's copyrighted work (whether books, articles or software), and no interest in any part of any revenue from such copyrights, but that patent revenue sharing and disclosure to the university of the patentable ideas is mandatory (IU), can one get around of any future claims for patents by simply releasing everything open-source and publishing all pre-prints before the university's patent office can get their hand on any of the research?

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    You need to talk to a lawyer, not just Random People on the Internet.
    – JeffE
    Commented Aug 4, 2013 at 3:06
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    "A patent is automatically invalid if the patented invention was published more than a year before the patent's filing date." So yes, the year is important. Commented Sep 29, 2014 at 10:23

2 Answers 2


Yes, in most cases, dissemination of a patentable invention by academic publication (papers, talks, code) constitutes prior art and will result in a later patent application being rejected. That is why people and institutions who intend to patent their discoveries are very careful about what they publish, and when. (Basically, publish after the patent application is filed.)

Regarding your patent evasion scheme, it would probably work in practice, but could lead to severe retaliation from your institution. You said yourself that the policy is to report all patentable inventions. By not doing so, and publishing without first enquiring whether your employer wants to patent the invention, you violate the policy... And, given your question, you would be doing so willingly and in bad faith. This sort of thing could get you fired. And, it could get the papers retracted (look at some of the examples of this on Retraction Watch).

Finally, one piece of advice: if you're so afraid that your employer owns the IP you create, enough to look for strategies to remove from them some of the IP they pay you to create, you should consider quitting. It doesn't look like you have a healthy relationship with your employer.

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    Your suggestion for unconditional quitting is misguided, and your presumption that everyone in universities is compensated for their time, on the merit of what their time is worth, is misinformed.
    – cnst
    Commented Aug 4, 2013 at 23:33
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    @cnst my point exactly! If you strongly feel you are not compensated for what you're worth, quit and find another job... But feeling that you are underappreciated definitely doesn't qualify as a reason to violate a contract you signed
    – F'x
    Commented Aug 5, 2013 at 7:21
  • F'x you are assuming full employment.
    – PatrickT
    Commented Feb 1, 2014 at 9:02
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    Actually, if you're employed by the university and publish in violation of university policy, you're not only opening yourself up to being terminated, but to lawsuits. This is particularly true in this case where you're violating the policy in bad faith (e.g. with the intent to deprive them IP owned by them.) And, no, this does not assume full employment.
    – reirab
    Commented Sep 29, 2014 at 1:37

In response to your specific questions, yes, it is significant that the disclosure occurred more than a year before the patent was filed. In the U.S., there is a one-year "bar-date" after public disclosure of the invention covered by a patent. Most of the rest of the world does not allow any period between disclosure and patenting; once you've disclosed, the invention is no longer patentable in those countries (though it may still be patented in the U.S. for up to a year.)

As noted by F'x, sabotaging your employer's patent claims is a sure way to make a lot of trouble for yourself.

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