When your own patent application counts as prior art: Beware the Continuation-In-PartNovember 11, 2021

Often during patent prosecution new technologies, concepts and data grow out of an original filing. How can you protect those new innovations? The natural reaction is to file a child application off of the parent filing, in order to preserve the earlier priority date through a continuation or continuation-in-part (CIP) application.

A continuation is limited in scope to the parent application’s disclosure. Therefore for the purpose of adding new subject matter, a continuation case isn’t an appropriate solution. A (CIP) application allows new subject matter to be added to the existing disclosure of the parent application, while the priority date for claims based on the original disclosure is retained.

As outlined in MPEP 211.05, new claims in the CIP application will inherit the priority date of the parent where the claims are disclosed in a manner such that the parent case contains a written description of the invention, and of the process of making and using it such that it enables any person skilled in the art to make and use the invention, and sets forth the best mode contemplated by the inventor of carrying out the invention (35 U.S.C. 112(a)). Other claims without such support in the parent case will have the CIP’s filing date for the priority date. On its face, this sounds like a great path forward for protecting new innovations derived from an applicant’s existing patent application. However, filing a CIP comes with a few key watchouts.

The first drawback is the same as with filing a standard continuation application – a shortened patent term. Along with the preservation of the original priority date comes the limitation of 20 years from said filing date for any issued patent claims arising out of the new application.

The less obvious pitfall of a CIP, in addition to loss of patent term, is when the parent application also serves as prior art against you. For claims not appropriately supported in the original disclosure, the parent application is treated like any other reference under 35 U.S.C. §102(a), although the exceptions of §102(b) still apply. Therefore, if the parent application publishes more than a year before the filing date of the CIP, the earlier patent may be considered prior art.  The result is that an applicant has no later than 30 months (one year after the parent application’s publication) to file a CIP, before the parent application itself becomes prior art. The fact that the inventors are the same or that there is common ownership does not prevent the earlier application from being counted as prior art.(1, 2)

When considering how to best protect add-on enhancements to an existing patent application, be mindful that the benefit of preserving the original priority date for claims supported in the original disclosure may not be worth the risk of having the parent application count against you for prior art. Given the loss of potential patent term and this risk of having to overcome your own patent application or other prior public disclosures as prior art, file any application comprising new matter with 12 months of publication of the parent (even as a provisional filing) or file a new standalone application to seek the longest patent term coverage available.

  1. In re Chu, 66 F.3d 292, 296–97 (Fed. Cir. 1995) (holding that even though Chu’s “application claims to be a CIP of the Doyle patent,” some claims were not supported by Doyle alone, so for those claims “the Doyle patent was properly relied on as prior art”)
  2. Santarus, Inc. v. Par Pharmaceutical, Inc., 694 F.3d 1344 (Fed. Cir. 2012), where the Federal Circuit affirmed a district court’s finding that claims not entitled to the parent’s priority date were obvious in light of the parent patent.

Cassie J. Edgar, Patent Attorney and Chair of the Regulatory Law practice group, advises clients in intellectual property, regulatory law, crisis management, compliance, stewardship, lobbying, and matters with USDA, FDA, EPA, and FTC. For additional information, please visit MVS or contact Cassie directly via email at cassie.edgar@ipmvs.com.

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