Is there a national Registry of Expired Patents that one can search through for reference?

  • National of which country? – chempatent1981 Feb 28 '17 at 7:44
  • Not really. But why do you want it? As that may lead to an alternative solution which you might find useful. – Maca Mar 2 '17 at 8:31

Yes, there is a list. No, it is not exhaustive. In fact, the patent system is expressly designed for this purpose. We want people to know about expired patents and to use them as they see fit. The USPTO Patent Database provides patent images for all patents since 1970, and text files for all patents since 1976. Every patent issued before 4/10/2000 (as of this writing) is expired. Some patents after that date are expired, depending on whether the patent has been abandoned. There is no list of every single expired patent, but you can produce a list of the bulk of expired patents, and then search more recent ones on a case-by-case basis as necessary.

  • Are you sure about the 4/10/2000 date? The law has been 20 years from filing since 1995. Some patents actually do issue in less than 3 years from filing. Even then, Public Pair doesn't explicit state a patent has expired (at least I haven't seen that). – Eric Shain Apr 10 '17 at 17:54
  • In addition to my earlier comment, this answer doesn't deal with patent term extensions or the case where patents have expired due to non-payment of fees. – Eric Shain Nov 7 '17 at 15:38

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