United States patent law requires that claims particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention. 35 USC 112(b). If a claim fails to meet this requirement, it will be found invalid as being indefinite.

Determining whether a claim meets this requirement is easy when the issues are objective. However, the law recognizes that there are inherent limitations in language, and that absolute precision is not always obtainable. Nautilus v. Biosig Instruments, Inc., 134 S. Ct. 2120, 2129 (2014). Thus, the courts have attempted to strike a "delicate balance" between such inherent limitations of language and providing clear notice of what is claimed.

As such, the courts have permitted subjective language in a claim, provided that the specification includes sufficient guidance as to the scope of the claims. When confronted with indefiniteness issues, the courts closely study the supporting specification, and rely heavily on the specification when determining whether subjective claim language provides adequate notice to the public concerning the metes and bounds of the claims.

In a recent case, Sonix Technology Co., Ltd. v. Publications International, Ltd., the Court of Appeals held that the term "visually negligible" as used in a claim was sufficiently definite – in part because of the support in the specification. The Court found that:

The question whether something is “visually negligible” or whether it interferes with a user's perception, however, involves what can be seen by the normal human eye. This provides an objective baseline through which to interpret the claims. See Warsaw Orthopedic, Inc. v. NuVasive, Inc., 778 F.3d 1365, 1371 (Fed. Cir. 2015), cert. granted, judgment vacated sub nom. Medtronic Sofamor Danek USA, Inc. v. NuVasive, Inc., 136 S. Ct. 893 (2016), and opinion reinstated in relevant part, 824 F.3d 1344, 1346 (Fed. Cir. 2016).

Thus, the Court held that, "although the term may be a term of degree, it is not 'purely subjective.'" The Court compared the Sonix '845 patent to other patents that had claims that had been found indefinite.

For example, in Interval Licensing LLC v. AOL, Inc., 766 F.3d 1364, 1368–74 (Fed. Cir. 2014), the claim related to displaying content “in an unobtrusive manner that does not distract a user.” Only one example of an "unobtrusive manner" was provided in the specification. The Court held that the term was “a term of degree,” id. at 1370, “purely subjective,” id. at 1371, and that the claim language offered “no objective indication of the manner in which content images are to be displayed to the user,” id.

Datamize, LLC v. Plumtree Software, Inc., 417 F.3d 1342, 1351 (Fed. Cir. 2005) involved claims requiring an “aesthetically pleasing” look and feel for interface screens. 417 F.3d at 1348–49. The Court determined that such language rendered the claim indefinite because, although the written description did detail various elements that might affect whether a screen was aesthetically pleasing (such as button styles and sizes), it “provide[d] no guidance to a person making aesthetic choices such that their choices will result in an ‘aesthetically pleasing’ look and feel of an interface screen.” Id. at 1352. Without such guidance, the claim did “not just include a subjective element, it [wa]s completely dependent on a person's subjective opinion.” Id. In Datamize, the written description did not contain any examples of an “aesthetically pleasing” interface, nor did it “explain what factors a person should consider when selecting a feature” to lead to an aesthetically pleasing result. 417 F.3d at 1352.

The Sonix Court determined that Datamize and Interval Licensing involved terms that were subjective in the sense that they turned on a person's tastes or opinion: “aesthetically pleasing” and “in an unobtrusive manner". More importantly, the specifications supporting such claims did not provide sufficient explanation for interpreting the claim terms. As the Court stated in Sonix: "Our prior cases establish that the written description is key to determining whether a term of degree is indefinite."

Accordingly, when drafting patents that may inherently require the use of subjective terms in the claims, it is important to provide numerous and meaningful examples that will give reasonable guidance to one of ordinary skill in the art to interpret such terms.

A copy of the full Sonix decision is attached here.