The scope of patent protection for a patent is defined by claims which are located at the end of the patent. One of the difficulties in determining whether infringement occurs revolves around patent claim construction which determines the meaning of terms or language in the claims. As you might suspect, claim terms can have different meanings to different people. However, the meaning is supposed to be from the perspective of a Person Having Ordinary Skill In The Art, often referred to as PHOSITA. Nonetheless, even those in the technological field (i.e., PHOSITA) may have different understandings of the term. In order to arrive at a single meaning of a term, the courts look to the intrinsic record and extrinsic evidence in order to determine how the PHOSITA might understand that term. The intrinsic record includes the patent application and also the correspondence between the examiner at the patent office and the applicant. Since the correspondence is considered as part of the intrinsic record, to a certain extent, it is sometimes possible to guide the meaning of a claim term during prosecution by introducing a definition as illustrated by the following case.
In Tempo Lighting v. Tivoli (Fed. Cir. Feb. 10, 2014), the patent owner (Tivoli) asserted patent infringement against Tempo Lighting back in 2004. Tempo requested an inter-partes reexamination (IPR) on the asserted patent. Due to the slow progress on the IPR, the district court stayed the litigation for over eight (8) years. This long delay reflects the distaste that many district courts have for patent litigation, especially patents that are scientifically oriented.
During the IPR, the examiner defined the meaning of one of the limitations in the claims, using a dictionary, specifically, “inert to light.” The examiner indicated “inert to light” means that the material does not degrade when exposed to light. Based on this definition, the examiner invalidated all of the claims based on the prior art.
The patent applicant appealed to the Board of Patent Appeals and Interferences (“Board”). The Board rejected the examiner’s claim construction. Instead of referencing extrinsic sources (i.e., dictionary), the Board looked to the intrinsic evidence (i.e., patent specification and the prosecution history of the patent) to define the meaning of “inert to light.” During prosecution, the patent applicant defined “inert to light” as being non-photo luminescent and not activated to glow by absorbing ambient light. The board adopted this meaning for “inert to light.”
The Federal Circuit affirmed the Board’s meaning or claim construction of “inert to light.” In construing the claims, the courts look to the intrinsic evidence first before it looks to the extrinsic evidence because the intrinsic evidence is considered more reliable. In doing so, the Federal Circuit found that the patent applicant expressly defined “inert to light” as being non-photo luminescent and not activated to glow by absorbing ambient light in responding to the examiner (i.e., in the intrinsic record or the prosecution file history). Also, the specification and the claims are not inconsistent with this definition.
Although the Board was right in how it defined the “inert to light” limitation, the Federal Circuit held that the board was wrong in relying on the examiner’s factual finding that the prior art disclosed the “inert to light” aspect of the claim. If the “inert to light” limitation has a different meaning to the board than it did to the examiner, then the board cannot adopt the examiner’s factual finding that the claims are not patentable. The board must remand for further consideration or make new findings of novelty and non-obviousness based on the board’s new definition of the terms.
Hence, the case was remanded with instructions to make new findings of fact based on the Board’s definition. This case illustrates that the terms used in the claims can be defined during prosecution. The claim terms can thus be defined in the patent application or after the filing of the patent application when responding to an office action. Each invention may be different and patent counsel should be consulted to determine the best course of action.
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