IP Newsletter | Winter 2016/17
	PATENT
	Doctrine of Equivalents: Alive and Well in Korea
	The doctrine of equivalents protects the patentee from competitors who appropriate the essence of the invention while strictly avoiding the literal language of the claims. Under the doctrine of equivalents, the scope of infringement is expanded beyond the literal confines of the claimed elements to capture "equivalents." Thus, even if a party's activity is outside the literal scope of a written claim, that party may still be liable for infringement if its activity is deemed equivalent to the claimed invention. While the contours of the doctrine equivalents in Korea is still quite new and has undergone several changes in recent years, the most recent case law confirms that the doctrine continues to remain viable, and may even be treated more broadly by some courts than before.
	"Immaterial/Material" Element Test
	In one of the earlier doctrine of equivalents cases in Korea (2009), the Supreme Court laid out a two-step test for determining equivalents: (i) determining whether the accused and claimed products are "identical to each other in terms of how the technical problem is solved"; and (ii) identifying whether each substitute element in the accused product is immaterial or material to the claimed invention (in view of the prior art, the conventional knowledge at the time of filing, and the patent specification). An accused product or process is considered equivalent to the claimed invention only if its substituted element is considered immaterial.
	Unfortunately, the Supreme Court's test failed to provide sufficient guidance regarding the specifics of implementing the test, such as defining the difference between an immaterial versus a material element.
	The "Same Core Technical Concept" Test
	Perhaps acknowledging the flaws of the "immaterial/material" element test, the Supreme Court subsequently appeared to reject the test in 2014. In a case that year, the court formulated a new test for determining equivalents that made no reference to the earlier test: an accused product would be equivalent for infringement purposes if any differences embodied in the accused product were insubstantial, and the accused product was deemed to practice the "same core technical concept" as the claimed invention.
	Unfortunately, the "same core technical concept" test has suffered from some of the same flaws as the "immaterial/material" test, in that the specifics are unclear. For example, determining "insubstantiality" can be problematic, because minor differences or changes can sometimes result in substantial improvements in effects or performance, and in such cases the accused device or process should not be considered equivalent even if the "core" technical concept is the same.
	The Latest Doctrine of Equivalents Case
	In a recent infringement case, the Seoul High Court largely applied the Supreme Court's 2014 test for determining equivalents, and notably included a detailed analysis of the doctrine of equivalents which has caught the attention of the Korean legal community. For one thing, the opinion appears to have left the door open to the possibility that an accused product can infringe under the doctrine of equivalents even if it completely lacks an element of the claimed invention (either literally or equivalently), as long as one skilled in the art readily could have conceived the omission.
	Outlook for the Doctrine of Equivalents in Korea
	The courts' latest application of the "same core technical concept" test appears to have broadened the pool of possible equivalents, since it can be expansively construed to include both products that are essentially equivalent but strictly avoid the literal language of the claims, as well as variants that share the same key components as the claimed invention but function in a substantially different way or yield a substantially different result. If the most recent case is any guide, patentees may want to reevaluate whether products or activities in Korea that do not literally infringe their patents might still infringe under the doctrine of equivalents, given that the current Supreme Court test is broadly worded and still less than clear. Of course, it is expected that the courts will further refine the legal test for determining equivalents going forward.
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	Young Hwan YANG yhyang.chang@kimchang.com H. Joon CHUNG hjchung@kimchang.com Woo Seok KIM wskim@kimchang.com
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