Let's say:

  1. Company A releases a software with a specific algorithm in January 2016. There are many proofs that the design of the software has been made before January 2016: customers have bought it in January 2016, press articles in January 2016 and after, many social media posts in January 2016. There are proofs of existence of the product in January 2016 from at least 100 different sources.

  2. Company A hasn't made any patent at all

  3. Company B releases a similar product today and registers a patent


  • Can Company B say "Dear Company A, you're not allowed to use this technology anymore because we have a patent for it", even if there are proofs of anteriority for Company A?

  • Can Company B sue Company A?

1 Answer 1


Companies don't just register patents. Patents are applied for. The process can take three or more years. Once filed, a patent examiner will evaluate the application to determine if it is 1) useful, 2) novel and 3) non-obvious. In the scenario you describe, company A's software would constitute prior art to company B's application and if the examiner is doing his/her job right would reject the patent application for lack of novelty. Of course, patent examiners might not find every instance of prior art so it is possible for Company A's product wouldn't be considered.

Company A can read company B's application when it publishes 18 months after filing. Many companies keep on top of evaluating patent applications to head off future problems. They can file opposing documents during the examination process. Should the patent actually be granted there are also procedures for challenging its validity.

Assuming company B gets a patent for exactly the same technology company A has already been selling (before the filing). Company B can sue company A. If they do, the suit can go to trial where company A would have an excellent chance of winning. If they do, then the precedent means company B's patent would be essentially useless. That said patent suits are very expensive and the companies may decide to settle with some sort of licensing agreement.

One additional thing to be aware of. Patents take time to acquire. It is not uncommon for the process to take 4 or 5 years. If company A starts selling their software in 2016 and company B gets their patent in 2017, then company B probably applied for their patent in 2013 or 2014. This means they indeed could had the idea first and the patent may indeed be valid.

  • Thank you for your helpful answer. I'm not sure to understand the second paragraph: Many companies keep on top of evaluating patent applications to head off future problems. They can file opposing documents during the examination process. How does this work? Does this mean Company A can look in a database of "in progress" patents (ie about to be registered), and say "Hey, I have a document showing we had this technology before."? Where is such a database open, is it free to browse?
    – Dove191
    Dec 16, 2017 at 1:26
  • As I said, patents don't get registered, they get granted. Patent applications publish 18 months after they are filed. Anyone can read them. You can go to patents.google.com, www.lens.org or other websites and search for patents or applications. There are procedures for filing prior art during the examination process to help the examiner consider all the relevant prior art.
    – Eric S
    Dec 16, 2017 at 2:37
  • @Dove191 just as an addition, patents get granted after years, so the applications are published way before they are granted.
    – user18033
    Dec 16, 2017 at 15:03
  • 1
    @Dove191 Please see the newly added last paragraph. If you find the answer adequate, please consider accepting it by clicking the check mark.
    – Eric S
    Dec 16, 2017 at 18:25
  • To expand on the "patents can take years" issue, using your example, it is possible that company B filed for a patent in 2005. If they disclosed what company B did in 2016, so long as a patent from that family was still pending, they could file in 2017 for claims that cover company B's product based on the disclosure in the 2005 patent. This is called continuation practice, and it is sufficiently confusing to people who don't do patents for a living that it often makes people think that a new patent can be applied for after somebody else invents the thing. It can't, but a continuation can.
    – Gary S
    Nov 17, 2019 at 4:27

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