[Patent Infringement Litigation in Korea - 2] Claim Interpretation under Korean Patent Law

1. 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.

2. 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.

 3. 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.