Equity for Whom? Defining the Reach of Non-literal Patent Infringement

Publication year1995


Equity for Whom? Defining the Reach of Non-Literal Patent Infringement

Peter K. Schalestock(fn*)

Outright and forthright duplication is a dull and very rare type of infringement. To prohibit no other would place the inventor at the mercy of verbalism and would be subordinating substance to form. . . . The doctrine of equivalents evolved in response to this experience.(fn1) One need not be a prophet to suggest that today's [decision] will . . . make enlargement of patent claims the "rule" rather than the "exception."(fn2) Under modem case law, the doctrine of equivalents is thought of by practitioners and the courts as simply a second bite at the apple for the patent owner in attempting to prove infringement.(fn3) [W]hatever role the doctrine of equivalents may have played in earlier times . . . today the doctrine is regularly used by patentees to seek greater coverage for their patents than the patent statute grants.(fn4)

The holder of a patent has a twenty-year monopoly on the manufacture, sale, or purchase of the device or process described in the patent.(fn5) The doctrine of equivalents allows a patent holder to bring an infringement claim against a person whose device is similar to the patent holder's, but is not literally described by the language of the patent. The doctrine originated as an equitable action to prevent fraud on patents by minor variation; it continues to develop through case law and is not included in the Patent Act.(fn6)

After a series of divergent opinions, the Court of Appeals for the Federal Circuit (CAFC)(fn7) has clarified the mode of analysis to be used in equivalents cases, requiring an element-by-element approach.(fn8) Additionally, in a bitterly divided en banc decision, Hilton Davis Chemical Co. v. Warner-Jenkinson Co. (Hilton Davis),(fn9) the CAFC recently held that equivalents analysis is available in all cases; a finding of equitable factors in the particular case is not required.(fn10) The Supreme Court has agreed to review the Hilton Davis case, marking the first time in nearly fifty years it will speak on the doctrine of equivalents. The CAFC is also examining the roles of judge and jury in equivalents cases. Its recent decision in Markman v. Westview Instruments(fn11) suggests that the court is quite willing to limit the participation of juries in patent actions,(fn12) and the Supreme Court has agreed to review the case. If upheld, Markman could presage a return of the doctrine of equivalents to its equitable roots by giving judges complete authority to decide claims arising under it.

The doctrine of equivalents began as a tool creating judicial flexibility to shield patent holders from piracy through minor variations on their inventions.(fn13) Over time, two trends have transformed it from shield to sword. First, plaintiffs have persuaded courts to allow claims of infringement by equivalents even where there is no evidence of copying or other fraud.(fn14) Second, as juries have decided more and more infringement cases, their sympathy for patent holders has had a greater impact on equivalents cases.(fn15)

Together, these trends have worked a gross distortion on the doctrine of equivalents. The doctrine should not be used to extend patent coverage, leaving the public unable to determine the exact scope of a patent's claims. Instead, application of the doctrine should be limited to cases where fraud or other equitable factors justify departure from the patent's terms. Further, decisions on infringement by equivalence should be made by judges in their equitable capacity, not by juries.

Part I of this Comment provides a brief summary of the history and present state of the doctrine of equivalents. It describes the contents of a patent and the difference between literal infringement and infringement by equivalents. This part then discusses the creation of the CAFC and the uncertain course of that court's early decisions in equivalents cases. Finally, this part presents the three issues at the forefront of equivalents analysis.

Part II discusses the recent resolution of the debate over the mode of analysis courts should employ in equivalents cases. It then describes the debate among the judges on the CAFC and that court's ultimate selection of a mode that circumscribes, at least slightly, the reach of equivalents claims.

Part III explores whether there should be a threshold equitable finding required to present an equivalents claim. This part describes the arguments on both sides of the question, tracing the increasingly strident debate among the judges of the CAFC. The discussion concludes with a critical look at the recent Hilton Davis decision.

Part IV examines the relative roles of judge and jury in deciding equivalents cases. This part describes the practical difficulties of separating issues between judge and jury and the reasons for having judges decide equivalents claims. Part IV concludes by discussing the impact of Markman and Hilton Davis on juries in equivalents cases.

I. Introduction

A patent includes claims that delineate the specific aspects of the device or process (such as shape, strength, temperature, or acidity), aspects that set the boundaries of the invention to be protected.(fn16) The legal rights of the patentee are defined by the claims, rather than the specification, which is a technical description of the patented device or process.(fn17) Literal infringement of a patent occurs when a person makes something that falls within the scope of the patent claims.(fn18) Because it is conceivable that a copyist could use the essence of the patented invention while making minor changes to escape the literal language of the patent, the doctrine of equivalents provides that infringement may be found if the accused device performs substantially the same function, in substantially the same way, to achieve substantially the same result as the patented device.(fn19)

The CAFC, created to provide uniformity and certainty in patent law, has struggled to provide a clear application of the doctrine of equivalents. After several years of debate, the court settled on a requirement that to infringe under the doctrine, an accused device must contain an equivalent for each element of a claim, rather than being equivalent as a whole.(fn20) Last year, the court issued en banc decisions affecting two other major areas of uncertainty in equivalents interpretation: (1) whether the doctrine is available in any infringement case or only upon a showing of equitable factors,(fn21) and (2) whether equivalents claims are triable to a jury.(fn22)

A. Summary of the Doctrine of Equivalents

By granting a patent, the government gives an inventor the legal right to exclude others from making, using, or selling the patented invention for a limited period of time.(fn23) The invention is described in the patent by means of claims and the specification.(fn24) The specification describes the device or process invented,(fn25) while the claims describe the scope of invention.(fn26) The claims define the legal rights of the patentee.(fn27)

For example, a hypothetical claim for a simple stool might read: "An object for sitting comprising a square seat of 3/4 inch plywood measuring 15 inches on each side supported by four legs, wherein each leg measures one inch by one inch and eighteen inches in length and is attached at a corner of the seat."(fn28)

A patentee who believes his patent has been infringed ordinarily must show that the alleged infringing product or process falls within the literal language of one or more patent claims.(fn29) However, strict application of this rule would allow infringers to escape liability by making minor, insignificant changes to avoid the literal language of the claims. In the example above, a functionally identical stool with the legs offset one inch from each corner would fall outside the claim language and not literally infringe. The doctrine of equivalents evolved to prevent this unjust result.

The most recent Supreme Court case to apply the doctrine of equivalents was Graver Tank and Manufacturing Co. v. Linde Air Products (Graver Tank).(fn30) The Court in Graver Tank set out a three-part test requiring an alleged infringing item (1) to perform substantially the same function, (2) in substantially the same way, (3) to achieve substantially the same result as the patented item.(fn31) If each part of the Graver Tank test is met, the infringer may be held liable even though the infringing device is not literally described by the patent claims.(fn32)

The doctrine of equivalents attempts to balance two competing policies of the patent system. The first policy is the "notice function" of patents, which gives the public clear notice of the metes and bounds of the patent so that inventors may design around existing patents and avoid infringement.(fn33) The second policy protects the interests of the patentee, preventing deprivation of patent benefits by unscrupulous competitors "who appropriate the essence of an invention while barely avoiding the literal language of the claims."(fn34)

The CAFC is currently struggling to balance those competing interests as it re-evaluates several important aspects of the doctrine of equivalents. One commentator observed that "while the Federal...

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