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Enabling an Inherent Upper Limit

Posted by James Juo | Apr 21, 2023 | 0 Comments

A patent's specification must describe the invention and “the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains . . . to make and use the same.” 35 U.S.C. § 112(a). For enablement, “the specification of a patent must teach those skilled in the art how to make and use the full scope of the claimed invention without undue experimentation.” MagSil Corp. v. Hitachi Glob. Storage Techs., Inc., 687 F.3d 1377, 1380 (Fed. Cir. 2012) (internal quotation marks omitted).

For an open-ended claim with an inherent, albeit not precisely known, upper limit, a two-part enablement test is set forth in Anderson Corp. v. Fiber Composites, LLC, 474 F.3d 1361, 1376–77 (Fed. Cir. 2007) (quoting Scripps Clinic & Rsch. Found. v. Genentech, Inc., 927 F.2d 1565, 1572 (Fed. Cir. 1991)):

[O]pen-ended claims are not inherently improper; as for all claims their appropriateness depends on the particular facts of the invention, the disclosure, and the prior art. They may be supported if there is an inherent, albeit not precisely known, upper limit and the specification enables one of skill in the art to approach that limit.

In Inc. v. ITC, No. 2022-1228, —F.4th — (Fed. Cir. Apr. 20, 2023), the Federal Circuit found enablement in affirming an ITC general exclusion order that applies to all infringing products, even those imported by entities that are not parties to the case.

The patented technology was high-density fiber optic equipment. The patent claim recited “a fiber optic connection density of at least ninety-eight (98) fiber optic connections per U space.” The term “U space” was construed to have its “plain and ordinary meaning, an example of which is a rack unit, which is a standardized measurement of 1.75 inches (44.45mm) in height within a standardized 19-inch rack or 23-inch rack.”

Substantial evidence supported the Commission's finding that skilled artisans would have understood, as of the patent's priority date of August 2008, that densities substantially above 144 connections per U space were technologically infeasible. The written description disclosed that the maximum density achievable using the LC-type simplex and duplex adapters available as of August 2008 was 144 connections per U space. And there was expert testimony that, despite market pressure, no commercial product had achieved a greater density than 144 connections using the LC-type simplex and duplex adapters. The MDC-type adapters that allowed skilled artisans to achieve higher densities were not developed until 2019.

In light of this evidence, the Commission properly held the open-ended claims have an inherent upper limit of about 144 connections per U space. In other words, the Commission properly construed the claim limitations to cover only connection densities up to about 144 connections per U space and to exclude higher densities.

There was no dispute that the claims would be enabled if they do not encompass densities above about 144 connections per U space.

The patent attorneys at Thomas P. Howard, LLC enforce patents and defend against infringement in litigation nationwide including in Colorado.

About the Author

James Juo

James Juo is an experienced intellectual property attorney. He has successfully litigated various intellectual property disputes involving patents, trademarks, copyrights, and trade secrets. He also has counseled clients on the scope and validity of patent and trademark rights.


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