TAKEAWAY: Disavowal of claim scope need not be explicit and may be inferred from descriptions deemed to be limiting in the patent specification.

In Techtronic Indus. v. International Trade Commission & The Chamberlain Group, decided on December 12, 2019, the U.S. Court of Appeals for the Federal Circuit reversed a ruling of noninfringement by the International Trade Commission (“Commission”) based on the construction of a claim term. In particular, the Federal Circuit held that whether an embodiment described in the patent specification is considered to define the outer limits of a claim term or is merely exemplary in nature is determined in the context of the how the patent was drafted.

The patent owner, The Chamberlain Group Inc. (“Chamberlain”), develops garage door openers and owns U.S. Patent No. 7,161,319 (“the ‘319 patent”), which includes claims reciting a “wall console.” In 2016, Chamberlain filed a complaint with the Commission against numerous corporations importing garage door openers into the United States, alleging infringement of the ‘319 patent. In the resulting investigation, the meaning of “wall console” was disputed by the opposing parties.

Although the plain and ordinary meaning of the term was acknowledged to be a “wall-mounted control unit,” the Administrative Law Judge (ALJ) determined that Chamberlain disavowed an interpretation that lacked a passive infrared detector. The ALJ noted that the ‘319 patent specification characterized the invention as a passive infrared detector contained in a wall control unit and distinguished the invention from retrofitted passive infrared detectors described in the prior art. In reviewing the ALJ’s claim construction, the Commission vacated the determination of noninfringement in concluding that the ‘319 patent disclosed multiple aspects of the invention, and every feature described as important is not imported into the claims.

On appeal, the Federal Circuit employed reasoning similar to that of the ALJ to reverse the Commission’s determination. The Federal Circuit held that disavowal of claim scope need not be explicit and found it was clear from the ‘319 patent that the core of the invention was a passive infrared detector included in a wall-mounted control unit. In particular, the Federal Circuit cited to the sole embodiment including a detector in the wall console, discouraging reference to prior art, and disclosure of an inventive solution rooted on the detector location as clearly manifesting the invention to necessarily include that feature.

In summary, the Federal Circuit concluded that where the specification describes the invention as having a particular feature, that representation may disavow claims directed to contrary embodiments omitting said feature. This case serves to remind applicants to take care to avoid representing the scope of an invention to the exclusion of other embodiments when drafting and prosecuting a patent application. An element disclosed as being a key feature or otherwise indispensable to the invention may be inferred in the claims even if not expressly recited.