Introduction to Patent Law

Anyone can apply for a patent for their own invention, but they may not prosecute a patent on behalf of someone else unless they are registered and authorized to practice before the PTO in patent cases.^¹ Authorization as an agent does not require the person to be an attorney, but the applicant must establish good moral character and must demonstrate he/she has sufficient legal, scientific, and technical qualifications to enable him or her to give meaningful assistance to patent applicants. In addition, the applicant must pass an exam administered by the Patent Office.^²

A registered practitioner is under an obligation to act zealously in representing a client,^³ and may be disciplined for violating ethical, legal, or PTO standards.^⁴ Disciplinary action may include suspension or exclusion from the right to practice before the PTO.^⁵

The one-day Patent exam is given in two parts. Both parts are three-hour, 50-item multiple choice exams. A score of 70 is required to pass. The questions are closely reasoned; each of the five alternatives must be carefully evaluated. The exam is open book, except the applicant may not refer to questions or answers from past exams.^⁶ The applicant may, however, refer to sections of the Patent code (35 U.S.C.), to the Code of Federal Regulations (37 C.F.R.), or to the Manual of Patent Examining Procedure (MPEP).^⁷ The MPEP describes the procedures which must be followed by both applicant and examiner during the prosecution of a patent. A computer-administered version of the exam is available.

The exam is usually given twice a year, in October and April. In the last four years, the median passing rate was 49%, with a range from 37% to 72%.^⁸

Claim drafting is a specialized art.^⁹ While the specification describes the best mode for practicing the invention, the claim describes its scope.^¹⁰ If you think of drafting a claim as if you were laying out the boundaries for a field, you would want to draw the boundaries so they were as expansive as possible. At the same time, you would want them to skirt, but not intrude into, your neighbor's fields.

"The applicant's duty to distinctly claim the invention is separate from the applicant's duty to set forth the invention in such full, clear, concise and exact terms to enable one skilled in the art to build the invention. . . . The distinctive claiming requirement is not to enable others to build the device but is instead to inform the public of the extent of the monopoly obtained by the patent owner."^¹¹

The claims are interpreted in light of the specification, the prosecution history, the state of the art at the time the patent was issued, and the problem the inventor was trying to solve.^¹² A claim for a balloon catheter described an inflation lumen (tube) "separate from" a guide lumen. The specification described a coaxial configuration, in which the wire guide lumen was enclosed inside the lumen used to inflate the balloon. An accused device was held not to infringe because it used a side-by-side configuration.^¹³

Many claims describe an invention in functional language as "a means for" achieving a desired result, without describing the structure or method to be used. In such cases, the claim is interpreted to cover the "structure, material, or acts" described in the specification.^¹⁴

Functional or "means for" language may not be used to cover the exact point of novelty, however, without more. "[A] characteristic essential to novelty may not be distinguished from the old art solely by its tendency to remedy the problems in the art met by the patent."^¹⁵ Claims describing the addition of "an inorganic salt" to rubber stock, as a means for producing a tire which was less likely than conventional tires to skid on a wet surface was upheld by the Court. The specification listed four examples of inorganic salts that would produce the desired result. The claims had been rejected by the Patent Office because the term "inorganic salt" described thousands of materials, some of which would be suitable and some not. The Court held the description was of a new combination of substances which was distinguished from the prior art.^¹⁶ "A limited use of terms of effect or result, which accurately define the essential qualities of a product to one skilled in the art, may in some instances be permissible and even desirable."^¹⁷

People who write patent claims try to make them as broad as possible, but the claims must be particular and distinct,^¹⁸ to provide clear warning to others as to what constitutes infringement, and to facilitate determining patentability by making a clear distinction between the patented device and the prior art, that is, by indicating what is novel about the invention. What language qualifies as sufficiently definite is judged by a standard of reasonableness under the circumstances. Descriptive terms such as "flexible," "about," "closely," "or similar apparatus," "effective amount," or "relatively small," may or may not be sufficiently distinct, depending on the context. A patent which described an invention as raising the bed of a paper-making machine to a "substantial" pitch, described in the specification as 12 inches or four percent, was sufficiently distinct.^¹⁹ Those skilled in the art clearly understood the term, "substantial elevation."

Most patents consist of a set of related claims or elements. Each element of the claims constitutes a limitation or narrowing of the scope of the claims preceding it. An accused device will not infringe the patent unless it contains all the elements of the claim, or an equivalent under the doctrine of equivalents. Court decisions refer to this as the "all elements rule,"^²⁰ or, in the case of methods claims, as the "all steps" rule.^²¹ In Smith & Nephew v. Ethicon, a surgical device was found to infringe a patented device used for anchoring sutures into bone, when the infringing device used all the same steps but merely added additional steps.^²²

As with other forms of legal interpretation, rules of construction have been proposed, but they are often contradictory.

"It seems to us that what we have said indicates how unsatisfactory it is to solve the problem of the meaning of a patent by resorting to minor canons of construction which, instead of providing reasons for a result provide only pegs upon which a result already reached in some other way may conveniently be hung. In consequence we prefer to decide the question of the meaning of a patent, not by heavy reliance upon subsidiary canons of construction, but rather by resorting to broad general principles applicable to the construction of all similar written instruments."^²³

There is a presumption in favor of ordinary meaning in interpreting claim language,^²⁴ but there are at least four ways of overcoming the presumption. (1) The patentee may act as "his own lexicographer," giving terms used in the patent special meaning.^²⁵ (2) Intrinsic evidence in the patent application may indicate which of several possible meanings was intended. (3) A term may be unclear, requiring reference to other intrinsic evidence. (4) Statutory authority may require that a claim be construed as covering the corresponding structure or step disclosed in the specification.^²⁶

Of course the inventor wishes to claim as much as possible. A claim for a method of analyzing medical tests to see whether, in the aggregate, the person's condition is normal or not doesn't just claim a system with inputs from lab tests, but a method for analyzing "any complex system, whether electrical, mechanical, chemical, biological, or combinations thereof."^²⁷ Leder and Stewart, the inventors of the "Harvard Mouse," claimed not only the transgenic mouse variety they created but all "non-human transgenic mammals" produced by their technique.^²⁸ Broad claims in the case of a pioneer patent may be upheld, but in an ordinary case they may not be. A competitor who believes the claims are overly broad as drafted may begin using a competing device and wait to be sued by the patent holder.

Because of the bias toward extreme generality in the wording of patent claims, it is important to read the entire claim, including the specification, in deciding what the patent covers. For example, Patent No. 6,004,596 for a "sealed, crustless sandwich" claims "a center filling sealed between the upper and lower fillings, and a crimped edge along the outer perimeter of the bread ..." The fillings are described as "jelly [or peanut butter] but may consist of any other edible substance such as . . . meat, vegetable oil, jelly, cheese, honey, or fruit." So what's new about this patent?

The patent describes a circular sandwich made of an upper and lower layer of dough or bread which is cut out by a mold. When the upper and lower parts of the mold come together, the mold crimps the edges of the bread. None of this is new; it's described in earlier patents. For example, the Lifshitz patent,^²⁹ cited as part of the prior art, describes a hexagonal mold which cuts out two circular pieces of bread containing filling between the pieces, and seals the edges by pressing them together. Two earlier patents (Kleiner, 1973, and Zobel, 1975) describe a method for sealing the sandwich edges by spraying them with dabs of tapioca starch, then hardening the tapioca by passing an alternating electric current through the bread layers as they are pressed together.

Sounds like a pop tart, doesn't it? What's new about the "sealed crustless sandwich" is that the peanut butter layers are larger than the small mound of jelly in the middle. When the bread is crimped by the mold, the edges of the top and bottom peanut butter layers are pressed together, sealing in the jelly. What's patented is a technique for making a convenience food sandwich with the jelly sealed in the middle so it won't leak out. Once it's crimped together, the sandwich may be wrapped in airtight packaging so it can be handled, shipped, displayed, and sold.

Patent claims may be written to be as broad as possible, but that doesn't mean all the claims, interpreted literally, would stand up if they were challenged. The description of the sealed, crustless sandwich says "meat, vegetable oil, jelly, cheese, honey, or fruit" may be substituted for the peanut butter, but it's hard to imagine that any of them would work as well as peanut butter as a sealant. If a challenge is raised, courts may narrow the interpretation of a claim, which may save the claim from invalidity but may also avoid a finding of infringement.^³⁰

It's not really in anyone's interest to hold a patent based on hollow claims, or based on a careless or incomplete prior art search. Patent examiners catch most of the mistakes and make the inventor revise the application, or reject the application outright. Competitors may point out prior art during an interference proceeding (described in Chapter 7). It's also much more expensive to defend a defective patent in court after it's been challenged than it is to do a thorough prior art search in the first place, and then write an accurate claim and specification. For a valuable invention, claim drafting is probably best left to competent experts.