How can I access an unpublished abandoned patent application?

Access to unpublished abandoned patent applications is limited. According to 37 CFR 1.14(a)(1)(iv), the file contents of an unpublished abandoned application may be made available to the public if:

• The application is identified in a U.S. patent, statutory invention registration, U.S. patent application publication, international publication of an international application, or publication of an international registration designating the U.S.
• Benefit of the abandoned application is claimed under 35 U.S.C. 119(e), 120, 121, 365, or 386(c) in an application that has been published or patented.

To obtain access, a written request must be submitted along with payment of the appropriate fee set forth in 37 CFR 1.19(b).