A patent gives its owner the right to exclude others from making, using, offering to sell or selling products or performing services in the United States that would infringe claims of that patent.1 To be valid, a claim must express exactly what the inventor of the patented invention created and described in a technical disclosure part of the patent and, at the same time, avoid being readable on what already existed in the prior art. The content and wording of the claims are negotiated between the patent applicant and an examiner at the U.S. Patent and Trademark Office (USPTO) during a process termed prosecution of the patent.
A claim has a preamble that usually describes the general field of the invention, followed by the body of the claim in the form of a number of paragraphs describing elements (also called limitations) of the claim. A typical patent contains a number of claims, often 20 or more. Some of the claims, termed independent claims, express the invention in its broadest sense and stand alone, that is, they do not refer back to any other claim. Another type of claim, a dependent claim, makes reference to one or more independent claims (or other dependent claims) and either adds an element or adds detail to an element already identified in the claim or claims on which it depends.
The Teeth of the Patent
A claim is infringed by a product or service that has all the elements of the claim. Infringement is usually avoided if any recited element in a claim does not appear in the product or service. The challenge to a competitor who hopes to use technology similar to what is covered by a patent is to design around the patent by creating a product or service that does not use one of more elements of any claim contained in the patent.
If every element of a claim is used in a product or service, infringement is said to be literal. The claims must be drafted and prosecuted with great care to maximize the possibility that competitors will literally infringe. However, it is very difficult to obtain a claim that aptly recites an inventor’s contribution to a technology, avoids the prior art, and yet remains broad enough to deter a potential literal infringer. Because the courts have been sympathetic to the patent owner when the heart of an invention, in essence, is appropriated but when literal infringement is avoided by inconsequential differences between design-around and claim wording, a so-called doctrine of equivalents has developed. This is an equitable doctrine that may apply when, despite the absence of literal infringement, there still may be infringement if the product or service in question has a structure or performs a function that is an equivalent of an element recited in the claim. Equivalences usually means that a claim element and its counterpart in a product or service do substantially the same thing in substantially the same way to achieve substantially the same result.2 Said another way, there is equivalence if the difference between the claim element and product or service counterpart is insubstantial. One indication as to whether the claim element and the corresponding structure or act in the product or service are equivalent is whether they are known to be interchangeable. If any element of a claim is not found, literally or equivalently, in a product or service, there is no infringement of the claim.
Because the doctrine of equivalents is an equitable doctrine, whether a patent owner is entitled to equivalence depends on what occurred during prosecution of the patent. If the patent applicant had to give up or limit some aspect of the invention in order to persuade the examiner to issue the patent, doctrine of equivalents entitlement becomes limited or is lost. This is known as prosecution history estoppel.
The Festo Decision
Until recently, there has been considerable uncertainty over whether a claim amendment only cuts back on the doctrine of equivalents, depending on how the claim was limited to sufficiently distinguish the invention over the prior art to obtain the patent or whether the amendment entirely eliminates equivalence. In Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co,3 the Supreme Court explained that any narrowing amendment relating to patentability that is made to a claim during prosecution eliminates equivalents for the surrendered subject matter except under certain exceptions that will seldom occur.4
The Festo decision creates a new paradigm for prosecution strategy, a paradigm in which the narrowing of claim elements by amendment must be avoided whenever possible.5 The art of navigating around Festo is beyond the scope of this article,6 but what is clear is that, for a patent to have true value, it will have to be drafted and then prosecuted prudently with the objective of having claims that will be infringed literally.
If a patent is not literally infringed and the doctrine of equivalents remains the only option for capturing infringements, it may be difficult for the patent owner to prevail. Even if there are no amendments during prosecution of a patent, infringement actions that have to rely on the doctrine of equivalents may not settle early, or at all, because the outcome is uncertain, empowering an aggressive competitor. If the patent is of such scope that a competitor may be able to easily design around it to produce a product or service that still has commercial viability, the patent has little value. Now, more than ever, to be worthwhile a patent must have claims that will be infringed literally by those commercially viable competitor products and services the patent owner wants to confront. Reliance on the doctrine of equivalents should be avoided whenever possible.
The Art of the Claim
There is an art to claim drafting. The challenge is to produce a patentable claim that will literally cover any commercially viable variant of the inventive product or service. For patentability, the invention must be novel,7 that is, different is some way when compared to earlier technology. It also must be unobvious in view of what was done before.8
Before preparing the broadest claim of a patent, the patent drafter should have a meeting with the inventor to gain an understanding of the invention at its most fundamental level. During this interview, the patent drafter should encourage the inventor to describe related products or environments to which the invention applies, alternative components and embodiments that could be used to practice the invention and solutions that were initially considered but discarded in favor of the solution currently disclosed. Learn about the technology employed by competitors, the direction competitors are likely to take in future technology and how the client may vary the technology in future product generations.
Structured Claim Drafting
Drafting the broadest claim that is possible, based on the technical description to be used in the patent application and prior art known to the inventor, requires a structured approach. First, list those elements of a product or service sought to be protected and note the structural and functional relationships among the elements. Then analyze each element, together with its function, to answer the following questions:
- Is the element necessary for preserving the desired functionality of the invention?
- Is that element needed for distinguishing the invention over the prior art?
An element necessary for the invention to function in the manner intended must appear in every claim. Any element unnecessary for functionality should be in the broadest claim only if the element both is commercially important to the invention and is novel in the context of the invention. Otherwise, the element should be discarded at least from the broadest claims. Then, the following two questions are posed for the remaining elements:
- Can the element be generalized or broadened in terminology without compromising claim novelty?
- Can elements be combined into fewer, more general, elements without compromising claim novelty?
Finally, review the entire claim and discard any words not absolutely necessary for functionality or novelty. Sanitizing the wordage, generalizing terminology and combining claim elements will improve the likelihood of literal infringement because a competitor will find it more difficult to argue persuasively that a claim element is missing from its competitive product or service.
An Example
A specific example will help illustrate structured claim drafting. Current home entertainment systems use multiple speakers distributed throughout a room for reproducing sound from music sources or movies. Every room has one or more "sweet spots" where the sound is best. The positions of these sweet spots arise as a result of reflections of sound within the room. These reflections of sound depend on the shape of the room; acoustic characteristics of the floor, walls, and ceiling; locations and design of the speakers; how the speakers are driven by the audio equipment; and other factors. A homeowner will want to sit at a sweet spot to have the best sound. Assume the invention to be an electronic system that detects where in the room a person is sitting and adjusts automatically the way that the speakers are driven by the audio equipment to coincide the sweet spot with the person’s seat. This is done by using an infrared detector to spot where the person is sitting and vary amplitude and timing of audio signals to the individual speakers to place the acoustic sweet spot there. It is easy to visualize this system. One need not have an engineering background to follow the example.
Assume that the invention will be adequately disclosed in the application. These are the components of the system initially disclosed by the inventor:
A switch to turn the system on or off
An amplitude control circuit for varying strength of signals sent to the speakers
A phase control circuit for varying timing of signals sent to the speakers
- An infrared detector that identifies where a person is sitting in the room
- A microprocessor that controls the amplitude and phase control circuits so as to vary the location of the sweet spot until it coincides with where the person is sitting
- A memory for storing prior sweet spot locations
- A pair of displays that show graphically where the system believes the person is sitting and when the sweet spot is correctly positioned to coincide with that spot
- A manual override to permit adjustment of the control circuit so as to fine-tune the sweet spot location.
- A claim based on these components may initially read as follows because all the elements envisioned by the inventor may be included in the first claim draft.
Claim
(Preamble) An audio control system for supplying audio signals produced by an audio signal source to multiple speakers distributed in a listening room, comprising:
(Body of claim) a switch to turn the system on or off;
an amplitude control circuit for varying relative signal amplitudes of signals sent from the source selectively to the speakers;
a phase control circuit for varying relative timing of signals sent from the source selectively to the speakers;
an infrared detector that detects the location of a listener in the room;
a microprocessor configured to be responsive to the detector and programmed to control the amplitude and phase control circuits so as to center an acoustic sweet spot for sound produced by the speakers at the listener’s location;
a memory for storing data relating to sweet spot locations in the room;
a first display unit controlled by the microprocessor that displays graphically the position of the listener in the room;
a second display unit controlled by the microprocessor that displays an indication when the acoustic sweet spot and listener location coincide; and
a manual override to permit fine tuning of the amplitude and phase control circuits by the listener.
The claim elements are now analyzed using the described procedure. In step one, shown in Figure 1, each element is examined to determine whether the element is necessary to enable the invention to achieve its intended function. Figure 1 demonstrates that, among the elements listed, only the amplitude and phase control circuits, infrared detector, and microprocessor are necessary for the system fundamentally to operate. The memory for storing prior sweet spot locations, although convenient, is not necessary. The on/off switch, displays and manual override are similarly not necessary for the system to carry out its intended function. (Please accept these premises for the purpose of this example.)
In step two, each element of the claim is reviewed to determine whether the element is novel within the context of the invention. In this example, the amplitude and phase control circuits are novel, as are the infrared detector and manual override. These components of course are known to be implemented in other systems, but that does not matter for this analysis. Although displays are known, display of acoustic sweet spot information is novel.
Any claim element not needed for functionality or novelty is removed. Only those claim elements that are necessary for functionality or novel within the context of the invention will remain initially in the broadest claim. In this example, the memory and on/off switch will be removed from the claim. The elements that remain are listed in Figure 2.
FIGURE1: CLAIM ELEMENT ANALYSIS
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FIGURE 2: TERMINOLOGY LEADS TO NOVELTY
(Can a broader term be applied to remaining claim element?)
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In step three, the remaining elements (Figure 2) are candidates for broadened terminology. In this example, the term microprocessor can be broadened to signal processing circuitry. This is a useful change because it will preemptively dispose of any argument over what constitutes a microprocessor for infringement analysis. The term infrared detector can be broadened to detector, since an infrared-type sensor is not needed to preserve novelty. The claim elements as now evolved are listed in Figure 3.
FIGURE 3
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In step four, the elements of the claim are next reviewed for combinability with other elements. Consider whether the function or structure of any claim element overlaps with the function or structure of another element. The elements amplitude circuit and phase circuit can be combined and imported into the term "signal processing circuitry" without compromising claim novelty. A broad claim as it has evolved so far now may read as follows:
An audio control system for supplying audio signals produced by an audio signal source to multiple speakers distributed in a listening room, comprising:
a detector that detects the location of a listener in the room;
signal processing circuitry responsive to the detector and configured to control amplitude and timing of audio signals supplied from the audio signal source to the speakers so as
to center an acoustic sweet spot for sound produced by the speakers at the listener location;
a display controlled by the signal processing circuitry to display, selectively, the position of the listener in the room, and when the acoustic sweet spot and listener location coincide; and
a manual override to permit fine tuning of signal processing circuitry by the listener.
Testing the Claim
After a broad claim is developed using the described structured approach, as a final test, ask the inventor to attempt to hypothetically design around the claim, proposing non-infringing embodiments that carry out the desired functions of the invention while avoiding the known prior art. If the inventor can design around the claim, while avoiding the prior art and still producing a commercially viable product or service that uses the concept of the invention, it is back to the drawing board. In this example, the inventor has explained that the display and override switch, although convenient and satisfying novelty, are not necessary to any product or service implementing the invention and that a system omitting those elements will retain novelty of the invention as a whole. A design-around eliminating those elements will retain commercial viability. Accordingly, the claim may be further broadened and read as follows:
An audio control system for supplying audio signals produced by an audio signal source to multiple speakers distributed in a listening room, comprising:
a detector that detects the location of a listener in the room; and
signal processing circuitry responsive to the detector and configured to control amplitude and timing of audio signals supplied from the audio signal source to the speakers so as to center an acoustic sweet spot for sound produced by the speakers at the listener location.
Conclusion
In the aftermath of the Festo decision, the art of claim drafting may be improved by a structured approach. A claim will be optimized by eliminating unnecessary wordage and limitations, improving likelihood that infringement will be literal. If infringement is literal, it becomes unnecessary to navigate around the Festo decision to preserve the doctrine of equivalents.
Footnotes
1 The claims are single-sentence statements at the end of the patent document that describe precisely what the patent covers.
2 See generally Warner-Jenkins Co. v. Hilton-Davis Chemical Co., 520 U.S. 17 (1997).
3 Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002).
4 The Court found that making any narrowing amendment relating to claim patentability creates a presumption that all equivalents are surrendered. The presumption is rebutted by establishing the equivalent in question to be unforeseeable at the time of the application, or that at the time of the amendment one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent. The patent owner may also attempt to rebut the presumption by establishing that the rationale underlying the amendment bears no more than a tangential relation to the equivalent in question.
5 Many pre-Supreme Court Festo decisions by district courts have been reviewed by the Federal Circuit to establish the types and circumstances of claim amendment that do not invoke a complete loss of equivalents entitlement. In general, any amendment to a claim element, other than a cosmetic one, will surrender subject matter falling in scope between the original and amended claim language. See, e.g., Pall Corp. v. PTI Technologies Inc., 259 F.3d 1383 (Fed. Cir. 2001) (narrowing may occur when amending an original claim); Pioneer Magnetics, Inc. v. Micro Linear Corp., 238 F3d 1341 (Fed. Cir. 2001) (when including limitations from a dependent claim in an independent claim); Mycogen Plant Science Inc. v. Monsanto Co., on rehearing, 261 F.3d 1345 (Fed. Cir. 2001) (when submitting a new, narrower claim). The estoppel effect of narrowing amendment also may be created even as to an unamended claim when a similar limitation was added to a parallel claim, thereby surrendering subject matter to overcome a rejection. Intermatic, Inc. v. Lamson & Sessions Co., 273 F.3d 1355 (Fed. Cir. 2001).
6 See McDermott Will & Emery’s IP Review, "Litigating Doctrine of Equivalent Cases in the Age of Festo," Page, 7 Spring 2004.
7 35 U.S.C. § 102.
8 35 U.S.C. § 103.
Stephen A. Becker leads McDermott Will & Emery’s patent procurement group. As a partner in the Firm’s Washington, D.C. office, Steve concentrates his practice on patents, with special emphasis on semiconductor electronics, telecom and computer-related inventions.
Marc E. Brown, a partner in the Firm’s Los Angeles office, concentrates his practice on software development and licensing, computer hardware, the internet and electronic systems.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
