As in many jurisdictions, a product-by-process claim (“PBP claim”) is often used in Korean practice to define a product invention, when there are no practical or convenient means to identify the product in terms of, e.g., structure or physical property. Since a PBP claim is defined by the process of manufacturing the product and not by its structure, there were two conflicting views as to whether the process limitation affected the scope of the claims at the stages of prosecution and enforcement. One view argued that the PBP claim should be construed as being directed to the resulting product regardless of the claimed manufacturing process; and the opposing view maintained that the recited process should be considered as a limitation of the PBP claim.  

In 2015, the Korean Supreme Court resolved the conflict regarding the patentability of a PBP claim by holding that the novelty and inventiveness of a PBP claim should be determined based on the structure and property/characteristics of the product that is defined by all the limitations recited in the claim, including the manufacturing process thereof (Supreme Court en banc Decision No. 2011 Hu 927 rendered on January 22, 2015). For a finding of infringement of a PBP claim, however, ambiguity remained as to whether a PBP claim would read on a product having the same structure as that of the claimed invention, even if the product was made by a different process. 

In a recent decision, the Korean Supreme Court removed the ambiguity, by holding that the standard for determining the protection scope of a PBP claim should be coterminous with that for determining the patentability thereof (Supreme Court Case No. 2020Hu11059 rendered on January 28, 2021). 

▶Background of the Case 

Korean Patent No. 1,399,514 (“the subject patent”) relates to a tablet containing polaprezinc made by a direct compression process, wherein 90% of the total particles in the tablet are not greater than 500 μm (i.e., D90 is less than or equal to 500 μm). 

Company A, one of the competitors of the patentee, lodged a negative scope confirmation trial with the Trial Board of the KIPO (Korean Intellectual Property Office), seeking declaratory judgment that its mode of practice did not fall within the scope of the patent claims. Company A’s argument was that its tablet differed from the claimed tablet in terms of its structure and material property due to the difference in its manufacturing process, i.e., a wet granulation process. 

The main issue was whether the process limitation of the PBP claim, i.e., the manufacturing process of the tablet, should be considered as one of the factors limiting the scope of the product invention. 

▶The Patent Court Decision 

The Patent Court noted that although the claimed tablet and Company A’s tablet both contained polaprezinc with particle size distribution limitations, the structure and characteristics of the tablets were uniquely characterized by their respective manufacturing processes. Since it was found that the physical characteristics and quality attributes of a tablet, such as flow, compaction, hardness, dissolution rate and stability, would vary depending on whether it was produced by a direct compression process or a wet granulation process, the Patent Court concluded that Company A’s tablet did not fall within the scope of claim 1. 

▶The Supreme Court Decision 

On appeal, the Supreme Court upheld the Patent Court’s decision and affirmed that Company A’s tablet fell outside the scope of claim 1, based on the following rationale:

In case that a claim directed to a product recites a limitation of the process for manufacturing the product, the subject matter of the claim should be the product resulting from such manufacturing process and the process limitation should be construed only as one of the vehicles for defining the structure and property/characteristics of the product. Therefore, when determining whether an accused product falls within the scope of the product invention recited in a PBP claim, the technical constitution of the claimed invention should not be limited to the manufacturing process alone, but should be determined based on all the claim limitations including the manufacturing process that may affect the structure and property of the resulting product. 

▶Implications of the Decision 

Unlike the U.S., where two different standards respectively apply to the patentability and infringement of PBP claims, the Korean Supreme Court has clarified through the present decision that the standard for determining the patentability of PBP claims in light of all the claimed features, including the process limitation, should also be applicable as the standard for determining the protection scope of PBP claims as well.