The claims define the scope of patent protection. Every word or phrase of a claim limits the scope of its protection and, during litigation, the court strives to give every word in each claim a meaning.40 When a potential infringer is being sued, the court takes every word into account, and the more that the invention, or one of its components, is described as being equal to something (i.e., that it “is” something), the courts will hold the patent owner to his or her own statements. Such language makes it harder for a potential infringer to be held liable if the alleged infringing device does not exactly match the description of the invention in the patent application. Phrases such as “may be” qualify statements made in the patent application and mitigate this issue.
The invention should therefore be described as, for example, “may be” having certain features as opposed to “is,” “having”, or “as having” those features. For example: the “mechanical clicker may be fabricated from a plastic material, but other similarly rigid material is also contemplated.” The reason is that, as has been explained before, the description sections of the patent application serve as a dictionary for terms in the Claims Set and a means by which the claims are interpreted. If the patent application describes the invention or its components as “is” something, the courts are more likely to construe the claims as requiring that characteristic when defining the scope of patent protection. If an accused infringer does not incorporate that “essential” characteristic, there would be no patent infringement and thus no patent infringement liability. However, when “may” is used to describe the invention’s features, the courts are less likely to construe the claims as requiring such features as essential to the invention when defining the scope of patent protection.
For example, in Cadence Pharmaceutical v. Exela Pharm Sci lnc.,41in which the patent owner (Cadence) sued the accused infringer (Exela) for patent infringement, the court had to give a meaning to the term “buffering agent” in the claims of Cadence’s patent to determine whether infringement existed. Cadence’s patent specification included potentially narrowing statements in relation to the concentration of the buffering agent as being between 0.1 and 10 mg/ml. However, the court did not construe the “buffering agent” limitation as limited to those specific concentration levels, because the patent specification stated they “may be” between 0.1 and 10 mg/ml. If the term “is” had taken the place of “may be” in this case, the court may have interpreted the buffering agent claim more narrowly, and Cadence may have lost its case against the infringer.
As discussed previously, specifics such as what the concentration of this buffering agent may be provide a backup argument for patentability downstream during examination so that claims can be narrowed if necessary. However, there is the potential for those specifics to be interpreted in such a way as to limit the claim, as illustrated by the Cadence case. To mitigate this possibility, the invention or aspects thereof should be described in terms of what the invention “may be” and not what the invention “is,” just as Cadence did. The more that the application states that an invention “is” something, the more likely it is that the courts will include that characteristic as a required limitation in the claims. However, stating that an aspect of the invention “may be” something mitigates the possibility that the courts will narrowly interpret the patent’s claims.
40. Normally, each word is defined according to its ordinary, dictionary meaning unless the inventor acts as his or her own lexicographer. However, to alter the common meaning of a word, the inventor must clearly express that intent in the patent specification or prosecution history.