You might think that "understandable patent claims" is an oxymoron. Patents are usually very challenging to read. The technology described may be difficult to understand, and the claims read like nothing else in the English language. Understanding a well-written claim can be hard. Understanding a poorly written claim might be nearly impossible.

All U.S. patent claims are governed by 35 U.S.C. § 112(b). The statute requires that:

"The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor … regards as the invention."

By requiring that patent claims "distinctly" state what is regarded as the invention, there should be no question as to what the claims describe. When claims are understandable, the statute is satisfied. When claims are difficult to understand, asserting those claims can become very complex.

Case law emphasizes the importance of clear, understandable claims, as in Halliburton Energy Services v. M-I LLC, 514 F. 3d 1244 (Fed. Cir. 2008):

"Because claims delineate the patentee's right to exclude, the patent statute requires that the scope of the claims be sufficiently definite to inform the public of the bounds of the protected invention, i.e., what subject matter is covered by the exclusive rights of the patent."

The statute and the case law make clear the essential need for clearly written claims. More importantly, however, decision-makers need to understand the claims in order for a patent to be granted and to subsequently have value. Numerous cases describe patent claims as defining the "metes and bounds of the invention," but if a U.S. Patent and Trademark Office examiner cannot understand the claims, then how can he or she perform a good examination to determine whether the patent should be granted? If a judge cannot comprehend the claims, then how can he or she perform the analysis that is necessary to determine whether infringement has occurred?

For the above reasons, the Patent Office takes a very strict view on the requirement for clearly written claims. If the meaning of the claim is unclear, i.e., if the subject matter that is regarded as the invention has not been "distinctly claimed," a competent Patent Office examiner will refuse to allow a patent application to mature into a patent grant. The Halliburton case further comments on this issue:

"We note that the patent drafter is in the best position to resolve the ambiguity in the patent claims, and it is highly desirable that patent examiners demand that applicants do so in appropriate circumstances."

Because the Patent Office has been tasked with the responsibility of ensuring that patent claims are clearly written, a small body of case law has evolved from the Patent Office's Board of Patent Appeals and Interferences (which is where applicants seek higher-level review of patent examiner rejections). The most well-known case dealing with the requirement of clear claim language, Ex parte Miyazaki, Appeal No. 2007-3300 (BPAI 2008), was an appeal in which claims directed toward the paper feeding unit of a printer were rejected because the claim language was indefinite (i.e., not clear). The claim in contention (in part) was as follows:

"A large printer comprising: … a paper feeding unit … located at a height that enables a user who is approximately 170 cm. tall, standing in front of the printer to execute the paper feeding process."

Claiming the approximate height of a person using the paper feeding unit does not convey where the paper feeding unit should be located. The board affirmed the rejection of the claim and stated that "because relative position of the user and the printer are not well-defined in the claim, the claimed height of the paper feeding unit does not present a structural limitation on the height at all."

Certainly, the best claims are the ones where there is no question as to the details of the claim. The more complex and convoluted the words within a claim, the greater the chance that the scope of the claim cannot be clearly understood.

It makes sense for the Patent Office to take a strict position on the definiteness of claims. Granted patents are subject to a presumption of validity. When issued, granted patents are presumed to be valid. Thus, a U.S. court has to honor that presumption and try to retain the validity of that patent. Courts, in fact, will engage in complicated analyses, and they will issue lengthy opinions in order to preserve the validity of a patent.

Take, for example, the recently decided case of Biosig Instruments v. Nautilus, Appeal No. 12-1289 (Fed. Cir. April 26, 2013). The invention was a heart rate monitor used for exercise. Sensors are placed on handlebars. A person places his or her hands on the sensor so that his or her heart rate can be measured during exercise. Note how the invention was claimed:

"A first live electrode and a first common electrode in spaced relationship with each other."

The obvious question is, "What is the meaning of the phrase 'in spaced relationship'?" This author, despite being an experienced intellectual property practitioner, is unable to look solely at the claim language and understand exactly what is being specified. Yet, in order to determine whether infringement has occurred, a judge would need to have a clear understanding of the meaning of that phrase. Take, for example, an accusation that a competitor is infringing the patent by manufacturing an exercise monitor that has "a first live electrode" and a "first common electrode." How can a judge look at the competitor's two electrodes and determine whether or not they are "in spaced relationship" with each other? The accused infringer's products need to be evaluated to determine if they include two electrodes "in spaced relationship." But, if the judge does not understand the meaning of the phrase "in spaced relationship," then the judge has no way to compare the accused infringing product with the claim to determine whether infringement has occurred.

At the district court level, it was held that the phrase "spaced relationship" was not distinctly claimed. In a 23-page opinion, however, the U.S. Court of Appeals for the Federal Circuit reversed, finding that the "spacing, size, shape, and material affecting the 'spaced relationship' … can be determined by those skilled in the art." The level of effort that the Federal Circuit made to arrive at that conclusion was significant. The court's analysis relied on the description from the patent specification, expert opinion and an expert report documenting a laboratory mock-up. The court's opinion acknowledged the effort:

"If the meaning of the claim is discernible, even though the task may be formidable and the conclusion may be one over which reasonable persons will disagree, we have held the claim sufficiently clear to avoid invalidity on indefiniteness grounds."

Did the Biosig court go too far? Maybe, but case law in Datamize v. Plumtree Software, 417 F.3d 1342 (Fed. Cir. 2005), necessitates the requirement that courts try very hard to honor the presumption of validity of the claims that they are adjudicating:

"The definiteness requirement does not compel absolute clarity … [and] … only claims not amenable to construction or insolubly ambiguous are indefinite."

The Biosig patent owner was able to go home from the courthouse with their patent intact. Nevertheless, litigating with a patent that has ambiguous terms can be risky business. Litigation costs will increase while plaintiffs struggle to explain the meaning of their claims. Additional expert testimony may be needed, as well. Claim language that isn't clear can be difficult to enforce.

There is a limit (albeit high) as to how far courts are willing to go to enforce patent claims with ambiguous language. The Biosig court acknowledges this fact:

"If reasonable efforts at claim construction result in a definition that does not provide sufficient particularity and clarity to inform skilled artisans of the bounds of the claim, the claim is insolubly ambiguous and invalid for indefiniteness."

If a court cannot be convinced that the claims are understandable, then patent rights will be lost. While Patent Office examiners are tasked with ensuring that granted patents make sense, patent applications sometimes fall through the cracks. It is ultimately the responsibility of patent attorneys (with their clients' cooperation) to ensure that patent claims are understandable, and that they clearly define the "metes and bounds" of the invention.

American folk singer Pete Seeger has been quoted as saying, "Any darn fool can make something complex; it takes a genius to make something simple." Leonardo da Vinci has been quoted as saying, "Simplicity is the ultimate sophistication." It may not be easy to draft a claim that is simple to understand. Claims by their nature describe complex concepts. But it is because the concepts are difficult that the claim language needs to be easy to understand. The judges, decision-makers, accused infringers and license purchasers have a much easier time making their decisions when they readily comprehend what they are reading.

Lawrence E. Ashery is an intellectual property attorney at RatnerPrestia with over 20 years of experience procuring patents, building portfolios, drafting legal opinions, counseling clients, and lecturing extensively throughout the United States and Asia. Contact him at leashery@ratnerprestia.com.