Supreme Court Denies Conclusive Prior Art Presumption of Preamble in Claims

This article was originally published on February 2017 by Young Mo Kwon and Un Ho Kim.

Under Korean patent practice, the elements recited in a preamble of a patent claim or description of related art of the patent specification was often considered as prior art. Specifically, the Supreme Court in 2005 held that the description of related art is presumed to be prior art (Supreme Court Decision 2004Hu2031Decided December 23, 2005).

However, a recent Unanimous En Banc Supreme Court Decision overruled this practice by ruling that the preamble in the claim and description of related art of the patent is presumed to be prior art only when supported by the specification and the prosecution history, while allowing for the presumption to be overcome under certain circumstances. On January 19, 2017, the Supreme Court ruled that principally, whether an element recited in a claim falls within the scope of prior art is a matter of fact, and thus, should be determined based on evidence. Under this principle, the Supreme Court determined that elements at issue are not prior art just because it is recited in the preamble of the claims or in the description of related art of the specification.

The Supreme Court allowed the prior art presumption of the preamble and description of related art only when the entire content of the specification and the prosecution history shows that the applicant admitted to and included the element in the preamble or description of related art to be prior art.

However, according to the Decision, this presumption is not conclusive, and may be overturned under certain circumstances. In the case at issue, the presumption was overcome when the patentee showed evidence that the technology disclosed in the preamble was proprietary technology that was yet to be disclosed at the time of application but disclosed at the time of filing a response to the examiner's rejection, and that the inadvertent disclosure occurred due to the patent drafter's mistake.

From a practical standpoint, this Decision provides the patentee an opportunity to rebut the presumption during a patent invalidity action even if the patentee mistakenly admitted or indicated certain element as prior art. Although it will be limited to certain circumstances, at least having such opportunity would still be invaluable. From a party initiating a patent invalidity action, on the other hand, it must conduct an additional prior art search to include the disclosure in the preamble or description of related art, which increases money and time.