What is the effective date of an abandoned application as prior art?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

The effective date of an abandoned application as prior art can vary:

• For published abandoned applications, the effective date is typically the publication date under 35 U.S.C. 102(a)(1).
• For unpublished abandoned applications referenced in other documents, the effective date is when the information became publicly available.
• The MPEP cites case law: “In re Heritage, 182 F.2d 639, 86 USPQ 160 (CCPA 1950), holds that where a patent refers to and relies on the disclosure of a previously copending but subsequently abandoned application, such disclosure is available as a reference.”
• Furthermore, “where the reference patent refers to a previously copending but subsequently abandoned application which discloses subject matter in common with the patent, the effective date of the reference as to the common subject matter is the filing date of the abandoned application.” This is based on In re Switzer, 166 F.2d 827, 77 USPQ 156 (CCPA 1948).