DOCTRINE OF EQUIVALENTS FILMA VARGHESE TRADE MARK DEPARTMENT
DOCTRINE OF EQUIVALENTS
The doctrine of equivalents is a legal rule in most of the world's patent systems that allows a court to hold a party liable for patent infringement even though the infringing device or process does not fall within the literal scope of a patent claim, but nevertheless is equivalent to the claimed invention.
The most often-quoted definition is from Graver Tank and provides that a device will infringe the claims of a patent under the doctrine of equivalents if it “performs substantially the same function in substantially the same way to obtain the same result” as the claimed invention.
The essential objective inquiry is: "Does the accused product or process contain elements identical or equivalent to each claimed element of the patented invention?" Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 117 S. Ct. 1040, 41 USPQ2d 1865, 1875 (1997)
HISTORY OF DOCTRINE OF EQUIVALENTS
Historically, courts took a literal approach to patent interpretation, based on established principles of legal interpretation. However, by the 18th and 19th centuries, this had come to be seen as unduly limiting on the scope of protection afforded to a patent-holder, especially as patent applicants are often required to describe new technology for which an adequate vocabulary has not yet been developed.
In response to this, the English courts developed a so-called 'pith and marrow' approach, which tried to distinguish between the essential and non-essential features of a patent claim when deciding infringement cases.
At the same time, courts in other countries, notably the United States, developed slightly different approaches to claim interpretation, of which the 'doctrine of equivalents' is perhaps the most famous. The equivalents doctrine takes a more holistic approach when comparing the patented invention with an alleged infringing device than did the 'pith and marrow' approach.
Attempts are ongoing at harmonizing the different approaches internationally; however, procedure is not getting much pace due to the disparity of the patent law in developed as well as the developing countries. The doctrine has been criticized as unduly vague, to the extent that it injects uncertainty and unpredictability to a patent system.
WHY DOCTRINE OF EQUIVALENTS?
The doctrine of equivalents is one of the most important aspects of patent law. The goal of the doctrine of equivalents is to provide patent owners with fair protection for their patents. The protection a patent confers is meaningless if its scope is determined to be so narrow that trivial changes to a device bring it out of the bounds of the patent.
Hence courts and legislatures face greatest challenge to create rules for determining patent scope that maintain the protection a patent is meant to confer while still keeping the patent monopoly within reasonable bounds.
CONCEPT OF CLAIMS AND PATENT INFRINGEMNT
Patent claims are the statutorily granted rights guaranteed by the State for a well-defined period of time to the patentee regarding the subject matter of the patent. These are the exclusive rights to prevent third parties, who do not have the patentee’s consent, from the act of making, using, offering for sale, selling or importing that subject matter of the patent.
The claim legally defines the patent’s scope of protection. The claims meaning delineates the subject matter that only the patentee may practice. Thus, a patent claim performs following objectives:
Public notice: A patent claim informs the public of the subject matter over which the patent provides exclusivity. Law requires every patent to have claims, and the claim’s preset location at the end of the specification is statutorily defined.
Defining patent scope: Patent claims actually establish the scope of exclusivity afforded to an issued patent. The claim tells the public the patent’s particular scope of exclusivity by defining the patent grant’s metes and bounds. This is the most fundamental trait of the modern patent claim. Through the claim’s words, the patent claim establishes the primary area of exclusivity the patentee will enjoy because of the patent grant.
Two stages of analysis for patent infringement enquiry
Stage 1: Literal infringement
Literal infringement examines whether the alleged device falls exactly within the boundaries of the claims of the patent by comparing the textual meanings of the claims with the features of the challenger’s device. When literal infringement is found, that is normally the end of the inquiry.
Stage 2: Infringement under the doctrine of equivalents
At this stage, claims are interpreted beyond their strict literal meaning and the scope of the claims may be extended to the features that are equivalent to those literally claimed.
FLOW DIAGRAM OF PATENT INFRINGEMENT ENQUIRY
APPLICATION OF DOCTRINE OF EQUIVALENTS
Doctrine of equivalents is a judiciary created concept (mostly, by the US courts), wherein the Judiciary has given certain tests in order to apply the doctrine. There are essentially two tests:
This test adopted by the Supreme Court is quite simple: "If two devices do the same work in substantially the same way, and accomplish substantially the same result, they are the same, even though they differ in name, form, or shape." Despite the seeming simplicity of this rule, its application to a particular case is often complex.
Substantiality of difference test
Determination of equivalency frequently involves conflicting opinions of experts and disputes as to scientific or engineering facts. The issue is often resolved by the testimony of expert witnesses and the decision may rest on which of the experts is the more believable.
BARS TO THE DOCTRINE OF EQUIVALENTS
The concept of Doctrine of Equivalents is not altogether a flawless concept.
Certain limitations for its application are:
All limitations rule : Under this rule, a finding of infringement may arise only when the doctrine of equivalents is applied on an ‘element by element’ basis. This means that the doctrine should be applied to each individual element of a claim and to the specific component substituted in the defendant’s product or process, not to the claimed invention as a whole and not to the overall defendant’s product or process.
Obviousness : An accused device or process cannot infringe under the doctrine of equivalents if it is merely an obvious variation of prior art inventions.
The rule of dedication: Where a patent application discloses unclaimed subject matter, the subject matter deemed to have been dedicated to the public. Therefore the doctrine of equivalents does not apply to that subject matter which is disclosed in a patent, but has not been claimed.
Prosecution History or File Wrapper Estoppel : Most patents are not issued with the claims originally filed. The claims of most patent applications are rejected, and the claims are amended with the inclusion of more detailed and restrictive language. If an examiner rejects the claims as not patentable over the prior art and the claims are amended to read more narrowly to avoid the prior art, the patentee is barred from asserting the claims in the broader sense. Since he or she gave up the broader construction to obtain allowance of the claims, the patentee is not permitted to assert that the broader construction is the equivalent of the claim which was finally allowed. The process of rejection and amendment followed by allowance is shown by correspondence in the Patent and Trademark Office file. That file history is contained in a heavy paper jacket known as a "file wrapper." As a result, the rejection of a claim followed by a narrowing and more limiting amendment is known as a "file wrapper estoppel".
The Means-Plus-Function claims - Under this provision, an element of a claim expressed in means plus function language "shall be construed to cover the corresponding structure, materials, or acts described in the specification and equivalents thereof."
COMPARITIVE STUDY OF DOCTINE OF EQUIVALENTS
The goal of the doctrine of equivalents is to provide patent owners with fair protection for their patents. The standards for determining equivalents are different in different jurisdictions. In US, a product or process is deemed to be equivalent if it performs substantially the same function in substantially the same way to yield substantially the same result. In UK, ‘variants’ amount to ‘equivalents’ to a patented invention. Although a variant may differ in appearance, form or even certain technical features, there can be infringement if they amount, in essence, to the embodiment of the same inventive concept and these modifications do not bring about a material change in the way the variant works.
Position in India
With reference to India, it can be concluded that so far there have been very few cases dealing with patent claim infringement. Nevertheless, the pace at which the technological development is taking place, the Indian judiciary is likely to face similar cases in near future. Moreover, taking into account the Patent Act, 1970, it is evident that no specification exists regarding the patent infringement and interpretation and interpretation of patent claims; to full this lacuna the courts can look into the principles and tests laid down by the US, UK and Japanese courts
Possible infringement of a patent claim must never be taken lightly. Issues of direct infringement, equivalency, file wrapper estoppels, and limitation of the claims to an invention as disclosed all must be considered before concluding that infringement does or does not exist.