In Abbvie v. Janssen (Fed. Cir. 2014), the claims of the patents at issue defined the claimed invention by its function, rather than by its structure. To put it in layman’s terms, it claimed a sports car going 0 to 60 mph within X seconds instead of claiming a V-12 engine having certain technical features that enabled the car to reach 0-60 in so many seconds. Functional limitations relates to the end goal, whereas structural limitations relates to specific structure allowing your invention to achieve those end goals. Patent claims defined as functional limitations are broader than structural language because functional claiming covers all structures capable of achieving such function. In contrast, structural limitations are limited to the specific structure in the claim that performs the function. Other ways of performing the same function are not usually covered with structure specific limitations.
When prosecuting a patent application, it is generally more desireable to obtain broader patent coverage because competitors have a harder time designing things that avoid your patent claims. However, broad functional claims are also more susceptible to challenges based on invalidity, obviousness, written description and other attacks. Narrower claims may be viewed as less valuable or desireable. However, narrower claims tend to hold up to invalidity challenges better than very broad claims. Thus, one claiming strategy is to layer your claims so that the claim set has independent claims of varying scope. Also, the claim set should include claims specific for a particular desirable feature or structure as well as broader clalims.
In AbbVie, the defendant challenged AbbVie’s functional claim language, which was written very broadly. In particular, the defendant attacked the validity of the patent claims based on the written description requirement. “The essence of the written description requirement is that a patent applicant … must describe his or her invention so that the public will know … that he or she has truly made the invention.” By claiming the invention based on functional language, the patent owner is asserting that he/she has invented and deserves the right to an entire functionally-defined genus. Accordingly, by functionally claiming a genus, the patent applicant is spreading a very broad net. However, it is sometimes difficult to show that the patent applicant invented and deserves the right to the entire functionally defined genus.
In this case, the claims were directed to an antibody binding to human interleukin 12 (IL-12). The claims at issue recited:
- A neutralizing isolated human antibody, or antigen-binding portion thereof that binds to human IL-12 and disassociates from human IL-12 with a k rate constant of 1 x 10-2 s-1 or less, as determined by surface plasmon resonance.
The claim defines the invention by its “binding” function, not its chemical structure or molecular structure. To satisfy the written description requirement for this functionally defined genus, the specification or patent application “must demonstrate that the applicant has made a generic invention that achieves the claimed result and do so by showing that the applicant has invented a number of species sufficient to support a claim to the functionally-defined genus.” In other words, the patent application must include so many examples of the species in the genus as necessary to show that the inventor invented the entire spectrum of the functionally-claimed genus. The full scope of the claim must be adequately supported in the written description.
Here, the patent application described 300 different species and alleged that it disclosed all known species except for the species embodied in the defendant’s product. However, the court found that the 300 different species belong to only one type of antibody which was not similar to the defendant’s product in many different aspects (e.g., type of heavy and light chains, % sequence similarity to Joe-9 antibodies and other differences). Thus, the written description did not give examples covering the entire ranges of functionally claimed antibodies.
As such, the Federal Circuit affirmed the jury’s finding that the claim was invalid for failure to satisfy the written description requirement. The Federal Circuit looked qualitatively to the types of species disclosed in the specification, not to the raw quantitative number of species disclosed.
The court recognized that “functionally defined genus claims can be inherently vulnerable to invalidity challenge for lack of written description support, especially in technology fields that are highly unpredictable, where it is difficult to establish a correlation between structure and function for the whole genus or to predict what would be covered by the functionally claimed genus.” In other words, the patent application may contain a number of different examples but one can never be sure if they have included enough examples when the technology is unpredictable. Future technology could change the way that one achieves a function. If so, the inventor would not be allowed to claim the entire genus because the application did not cover the future technology. As such, functionally defined claims would always be subject to possible invalidity issues.
A sound claiming strategy would be to include both functionally defined claims as well as more narrow structurally defined claims directed to generally the same subject matter. Also, include narrow specific structurally defined claims directed to desirable features of the invention.
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