Suppose a non-provisional Patent Application-A has requested on day-0 (filing date) a non-disclosure till grant date.

Now during the examination process for Patent-A a different patent application-B is filed by an unrelated inventor. Does the examiner working on this new application have access to the Application-A during his prior art search? Would disclosures in Application-A be treated as prior art for Application-B?

Keep application secret

1 Answer 1


Until an application is published it is not prior art. It is not accessible by an examiner but even it was it could not be used as prior art.

However, once it is published it can be prior art with the priority date of its filing. In the U.S., this means that it can be used to show another application is obvious as of the date of its filing even though no one could have seen it then.

In Europe, this type of prior art is good for showing lack of novelty as of filing date but can't be used to show lack of inventive step (EPO analog of obviousness) until the date of publication.

  • Thanks! So if I understand what you wrote correctly, patent-b may have no problems during the examination stage but later someone may be able to point to patent-a during post grant review or other proceedings and use patent-a to invalidate patent-b? Sep 14, 2019 at 3:10
  • if patent-a issues/publishes during the examination of patent-b, it could be used in a rejection. Otherwise, as you say, it could be used to invalidate patent-b either in the PTAB or the courts.
    – George White
    Sep 14, 2019 at 3:17
  • 1
    Thanks again! But isn't this unfair from a fundamental justice point of view. If some piece of information was not in public knowledge as of the priority date of Patent-B how could it have been expected to find it as prior art. Basically how can information that is hidden be treated as prior art. Sep 14, 2019 at 3:46
  • @curious_cat That is a fair question. It boggles my mind why the USPTO would allow to keep secret patent applications in the first place. At the EPO you may only request to publish an application ahead of the 18 months period, but in no way you can keep it hidden. A prior yet unpublished EP patent application may take away the novelty of your invention (not the inventive step) as George White pointed out, however the examiner shall carry out a search for such type of prior art after 18 months and prior to granting the EP patent. Sep 14, 2019 at 9:21
  • Originally applications in the U.S. were not published at all until and unless there was a grant. The idea is that the applicant could decide to withdraw an application and keep their invention as a trade secret unless they thought the protection they were getting was worth the disclousre. in 1999 Congress enacted a law that requires publication 18 months after the requested priority date due to international treaties. It does not apply if there are no counterpart foreign applications because of the historic idea that a disclosure was a trade for protection. No protection, no disclosure.
    – George White
    Sep 14, 2019 at 17:00

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