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Doctrine of equivalents |
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This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (June 2007) |
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. U.S. judge Learned Hand has described its purpose as being "to temper unsparing logic and prevent an infringer from stealing the benefit of the invention". Royal Typewriter Co. v. Remington Rand, Inc., 168 F.2d 691, 692 (2d Cir. 1948).
The goal of the doctrine of equivalents is to provide patent owners with fair protection for their patents. 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 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 (see below); however, progress is slow due to the long history of patent law in developed nations. The doctrine has been criticized as unduly vague, to the extent that it injects uncertainty and unpredictability to a patent system.
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In France, the doctrine of equivalents can be invoked if the accused device contains means having the same function in order to obtain the same result as the claimed invention.
In Germany, a device is considered to be equivalent if there is identity between the device and the claimed invention with respect to the problem and the effect, but not necessarily the "solution principle" (the manner in which the device operates).
Japan's doctrine of equivalents was first formalized in 1998, when Japan's Supreme Court held that equivalents are determined by considering (1) whether the difference relates to an important claim element, (2) the possibility for substitution without causing a failure to attain an invention's object and a change in the manner of attaining it, (3) obviousness of the substitution, (4) whether the accused item is an anticipated or obvious modification of state of the art, and (5) whether estoppel exists.
The United Kingdom has never employed a doctrine of equivalents approach. This was most recently asserted by Lord Hoffmann in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd (2004). As a signatory to the European Patent Convention (EPC), the UK follows the Protocol on the Interpretation of Article 69 of the EPC, which requires member states to draw a balance between interpreting patent claims with strict literalism (with the description and drawings only helping resolve ambiguity) and regarding the claims as a mere guideline only.
The latest UK case law on claim interpretation is found in 'Improver Corp v Remington Consumer Products Ltd' (1990) and the House of Lords decision in 'Kirin-Amgen' (2004). The so-called 'Improver' (or Protocol) questions found in the former are a widely-used three-step test for deciding infringement. Their usefulness in high-tech cases was, however, called into doubt by Lord Walker in 'Kirin-Amgen'.
In the United States, there are two tests for determining whether an accused device or process is deemed to be equivalent. Under the first test (Graver Tank & Manufacturing Co. v. Linde Air Products Co., (1950)), called the "triple identity" test, something is deemed equivalent if:
Under the second test (Warner-Jenkinson Co. v. Hilton Davis Chem. Co. (1997)) something is deemed equivalent if there is only an "insubstantial change" between each of the elements of the accused device or process and each of the elements of the patent claim. One limitation that has been placed on this doctrine is prosecution history estoppel, which prevents a claim from being made for infringement where the difference is something that the patentee had abandoned through an amendment to the patent. It is generally considered the case that the second test builds on the first test in a doctrine of equivalents analysis.
A doctrine of equivalents analysis must be applied to individual claim limitations, not to the invention as a whole.1
The United States also has a statutory equivalents doctrine that is codified in 35 U.S.C. § 112/6.
Attempt have been made to harmonize the doctrine of equivalents.
For instance, Article 21(2) of 1991 WIPO's "Basic Proposal” for a Treaty Supplementing the Paris Convention states:
The EPC 2000, which came into effect on 13 December 2007, included an amended "Protocol on the interpretation of Article 69 EPC" intended to bring about uniformity at a national level between contracting states to the EPC when interpreting claims.2 The amended text reads:
However, no definition of what was meant by an "equivalent" was included in the Protocol and it is expected that this lack of a binding definition will do little to achieve the desired uniform interpretation.2
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