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. US judge Billings 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 (CA2nd Conn) 168 F2nd 691, 692.

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 wholistic 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.

Standards for determining equivalents

United States

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:

1. It performs substantially the same function
2. in substantially the same way
3. to yield substantially the same result.

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.

Japan

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.

United Kingdom

The United Kingdom has never employed a doctrine of equivalents approach. This was most recently asserted by Lord Hoffman 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 be Lord Walker in 'Kirin-Amgen'.

France

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.

Germany

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).

Harmonization attempts

Attempt were made in the past 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:

"(a) (...) a claim shall be considered to cover not only all the elements as expressed in the claim but also equivalents.

(b) An element (“the equivalent element”) shall generally be considered as being equivalent to an element as expressed in a claim if, at the time of any alleged infringement, either of the following conditions is fulfilled in regard to the invention as claimed:

(i) the equivalent element performs substantially the same function in substantially the same way and produces substantially the same result as the element as expressed in the claim, or

(ii) it is obvious to a person skilled in the art that the same result as that achieved by means of the element as expressed in the claim can be achieved by means of the equivalent element."

On a strict European level, explicit introduction in codified law is planned as it can be seen in the new version of the European Patent Convention, the "EPC 2000" (pdf). The new protocol on the interpretation of Article 69 EPC states, in its new Article 2:

"For the purpose of determining the extent of protection conferred by a European patent, due account shall be taken of any element which is an equivalent to an element specified in the claims."

Landmark decisions

• United States
  • Graver Tank & Manufacturing Co. v. Linde Air Products Co., (1950)
  • Warner-Jenkinson Co. v. Hilton Davis Chem. Co. (1997)
  • Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., both Federal Circuit and Supreme Court decisions
  • Honeywell International v Hamilton Sundstrand Corp.(doc)
• United Kingdom
  • Catnic Components Ltd. v. Hill & Smith Ltd. (1982)
  • KirinAmgen v. TKT (October 21, 2004, decision "UKHL 46", regarding European patent EP 148 605)
• Germany
  • Batteriekastenschnur decision
  • Formstein decision

References

Johnson & Johnston Associates Inc., v. R.E. Service Co., Inc. The patentee was Johnston and the accused infringer was RES. The patent under question (Patent #1, granted in 2001 and claiming an "aluminum" substrate) had a claim that required "a sheet of aluminum". Johnston had also been granted Patent #2 claiming a "stainless steel" substrate in 1998, and Patent #3 claiming a generic metal substrate sheet in 1999. RES's accused process used steel. The specification of Johnston Patent #1 disclosed that aluminum was preferred but other metals could be used such as stainless steel and nickel alloys, also polypropylene could be used.

The jury trial found that there was infringement of Patent #1 under the doctrine of equivalence - steel was equivalent to aluminum. RES appealed to the Federal Circuit. The main issue on appeal was whether something was disclosed in the specification but not claimed, can the patentee receive coverage or is that thing given to the public? The Federal Circuit reversed the jury verdict finding that it could not be infringement as a matter of law - by disclosing a broad list of materials, and claiming only one, Johnson & Johnston had surrendered the remainder of the list to public use.

Sources

• Meurer, Michael J. and Nard, Craig Allen, "Invention, Refinement and Patent Claim Scope: A New Perspective on the Doctrine of Equivalents" (April 20, 2004). Boston Univ. School of Law Working Paper No. 04-03; Case Legal Studies Research Paper No. 04-5. [1]

See also

• Claim
• Prosecution history estoppel