New Supreme Court Decision on Doctrine of Equivalents in Korea

The rationales of the doctrine of equivalents in Korea are basically similar to those of the U.S. Namely, when an accused product or process performs substantially the same function in substantially the same way to obtain the substantially same result of the patented invention, the accused product or process infringes the patent right.

In particular, the Korean Supreme Court held that the accused product or process infringes a patent where an element of the patented invention is substituted with another element and, if (i) the technical concepts or principle to solve the objective of the patented invention and the accused invention are the same or common; (ii) the substituted element in the accused invention performs substantially the same function in substantially the same way to obtain the substantially same result of the patented invention; (iii) such substitution is obvious to an ordinarily skilled person in the art. However, the doctrine of equivalents shall not be applicable to the circumstances that (iv) the accused substitution was already known to skilled persons in the art at the time of filing an application and (v) the accused element was excluded from the claimed invention during prosecution.

On July 24, 2014, the Supreme Court further clarified the scope and meaning of the above (1) requirement of DOE; the technical concepts or principle to solve the objective of the patented invention and the accused invention must be the same or common.

The patent claimed a cutter for dry seaweed. The seaweed cutter has cutting blades laid out in a grid pattern. Seaweed is placed on top of the cutting blades and pressed from top to down and then sliding down into a container through a grid-patterned box attached to the bottom of the cutting blades. The patented invention can achieve a cutting and storing of seaweed in a single process.

The accused cutter is different from the patented cutter in which the accused cutter has moving blades that move from top to down and cut seaweed. Instead, the patented invention does not have moving blades. Except the position of blades, other technical features of the two devices are the same. Two cutters perform the same function in the substantially same way and achieve the same result.

However, the Seoul High Court denied patent infringement under DOE because the accused cutter did not meet the (1) requirement of DOE. The accused cutter cut seaweed in a different way from the patent technology; there is no the same technical principle of resolving the technical problem.

The Supreme Court vacated the lower court decision. The Court held that the "essence or core of the technical idea" must be determined between two cutters in order to apply DOE and then found that two cutters used the same technical idea because it should be the incline of the grid patterned box that allowed seaweed to be automatically stored after being cut and it is found in two cutters although two cutters employed different embodiments. The Court found that the change to position of the cutting blades was obvious. The Supreme Court decision clarified (1) requirements of DOE under the Korean patent law. In practice, patentees may have higher chance to apply DOE under the recent decision.

Basics on Claims under Korean Patent Law

1. Description requirement

Article 42, paragraph 4 of the Patent Act stipulates: "claims shall be supported by the detailed description of the invention and shall define the invention clearly and concisely." Claims must be supported by the detailed description of the invention. That means that the scope of each claim must be identical or equivalent to the subject matter described in the detailed description. Thus, an applicant should draft a specification to include a wide variety of examples with respect to the claimed invention.

KIPO maintains a rather strict attitude towards the support requirement through its narrow interpretation of the scope to be supported. As a practical strategy, a divisional application rather than an amendment of claims may be used to secure the broader scope of the protection and avoid prosecution estoppel. But, because it is required that the scope of a divisional application be within the scope of the original specification, in order to secure a broad scope of protection the original specification should include sufficient examples and the descriptions of its equivalents to support the claimed subject matter.

2. Claim Interpretation

  All Elements Rule

The scope of a patent is defined by the elements of a claim. It is well settled that each element in a claim is deemed material to defining the scope of the patented invention. Therefore, only when every element defined in a claim is found in an accused product or process, the accused product or process literally infringes the patent right.

  Doctrine of Equivalents

It has been long time for the Patent Court and the Supreme Court to adopt the doctrine of equivalents as a part of Korean patent law for interpreting claims.

The rationales of the doctrine of equivalents in Korea are similar to those of the U.S. Thus, it is true that if the accused product or process performs substantially the same function in substantially the same way to obtain the substantially same result of the patented invention, the accused infringes the patent in Korea.

In particular, the Supreme Court held that the accused product or process infringes a patent where an element of the patented invention is substituted with another element and, if (i) the technical concepts or principle to solve the objective of the patented invention and the accused invention are the same or common; (ii) the substituted element in the accused invention performs substantially the same function in substantially the same way to obtain the substantially same result of the patented invention; (iii) such substitution is obvious to an ordinarily skilled person in the art. However, the doctrine of equivalents shall not be applicable to the circumstances that (iv) the accused substitution was already known to skilled persons in the art at the time of filing an application and (v) the accused element was excluded from the claimed invention during prosecution.

  Prosecution History Estoppel

Based on the doctrine of equivalents, a patentee cannot regain his rights to any elements that were abandoned through an amendment or a response during prosecution. For example, when an element is excluded through an amendment in order to secure novelty and non-obviousness in response to the examiner’s rejection, an invention with an equivalent element is outside the scope of the patent.

The Supreme Court held that prosecution history estoppel should be applied in view of specification, opinions of an examiner from filing of the application to issuance of a patent and the intent of an applicant as indicated in the amendments and arguments during prosecution. Furthermore, in a patent containing more than one claim, the prosecution history of each claim should be independently reviewed to decide whether certain subject matter was intentionally excluded from the scope of the claim.