US patent claiming Compound A or its salt (X salt included in laundry list) published after another US application filed as compound A's X salt and gets grant. They do not share common priority and inventors except applicant. Later patent can be challenged or can earlier patent be prior art for later patent?

  • Are you saying they do have one common inventor?
    – George White
    Jul 22, 2019 at 21:34
  • No common inventor but applicant is same
    – Nsn
    Jul 23, 2019 at 8:13

1 Answer 1


It is all about the filing dates. If application A is filed first then application A may be considered prior art for application B even if application B is filed before application A publishes. It doesn't matter whether or not application B was developed independently of patent A. This is true even if the application A never gets granted as a patent.

I am not a lawyer and this is not legal advice.

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