Because No One is Immune to the Law
October 28, 2021 - United States, Intellectual Property

Traversing Higher Hurdles for Functional Limitations Under Section 112

PTAB Rejects Tribal Immunity Proceedings

Genus claims have long been an important component of patent strategy, extending coverage around a lead compound to stop would-be competitors. Recent decisions from the Federal Circuit, however, highlight a tightening standard for written description and enablement of genus claims for biologic inventions, leading some legal scholars to proclaim the “death of the genus claim.”[1] 

While we think reports of the death of genus claims are a bit premature, such claims are becoming more and more challenging to obtain during prosecution and to enforce in litigation. In particular, antibody claims that do not recite CDR sequences raise the specter of being subject to written description and/or enablement challenges. Likewise, functional language, while potentially helpful to distinguish claims from prior art, is becoming increasingly problematic. 

The following are several practice tips for protecting biologic innovations in view of the current trends.

Practice Tips

  • To borrow an analogy the courts have returned to repeatedly, if a genus is a plot of land, the disclosed species and guidance regarding subgenera should cover as much of the terrain as possible.[2] It is important to build subdivisions into your property and include layers of subgenera that reduce the size of the plot (and total number of species). In the current climate, providing as many representative species as possible is more important than ever.
  • When considering the level of disclosure to include in an application, keep in mind that the test for written description is the same whether a claim element is essential or auxiliary to the invention. Add language to the description and layers of backup positions for elements that represent emerging technologies or less predictable fields.
  • Functional limitations “raise the bar” for enablement and written description. Carefully consider the necessity of each functional limitation in the claims. It is essential to provide support for all functional elements of the claims and build in appropriate backup positions and crystal-clear roadmaps for identifying species that meet the functional limitations. Whenever possible, structural motifs common to the members of a genus or subgenus should be identified to support a structure-function correlation.
  • Despite increasing challenges for written descriptions and enablement of a functionally defined genus, functional limitations remain an important component of patent strategy for antibodies and related technologies, including in jurisdictions such as Europe and Japan. Patent applications should include support for multiple layers of claim scope, including claiming antibodies by epitope.

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[1] Karshtedt, Dmitry, Lumley, Mark A., and Seymore, Sean B., The Death of the Genus Claim (Aug. 5, 2020), Harvard Journal of Law & Technology (available at

[2] Amgen Inc. v. Sanofi, 987 F.3d 1080, 1084 (Fed. Cir. 2021), citing AbbVie Deutschland GmbH & Co. v. Janssen Biotech, Inc., 759 F.3d 1285, 1299-300 (Fed. Cir. 2014).