IP Newsletter | Fall 2018
	PATENT
	Supreme Court Makes It More Difficult to Protect Inventiveness of "Numerical Limitation" Inventions
	A recent Supreme Court case in Korea (2016Hu564 rendered on June 28, 2018) has reaffirmed the difficulty of patenting "numerical limitation" inventions in Korea, where the numerical limitation is the only distinguishing feature compared to the prior art.
	"Numerical limitation" inventions are so-called because at least one essential element of the invention is defined as a numerical range of values (e.g., a range of sizes, weights, or amounts), thus limiting the scope of the invention to that specific range of values. Numerical limitation inventions are often difficult to patent in Korea because commonly the numerical limitation is the only feature that distinguishes the invention from the prior art. Under Korean law, such an invention must show that the numerical limitation has "critical significance" in order to be found patentable (meaning that values for the numerical element within the claimed numerical range all produce some different or remarkable effect over the prior art, and that such effects do not occur outside the claimed range). Since this is usually difficult to do, patent applicants generally try to avoid having their inventions characterized as numerical limitation inventions in order to avoid such additional patentability requirements.
	The subject case involved a patent for a bioreactor that used a ceramic membrane filter to facilitate production of lactobacillus bacteria in high densities. The history of the patent is complicated – after the patent was initially invalidated through an invalidation action at the IPTAB, the claims were corrected (i.e., amended) to add two features: specifying that the ceramic membrane filter was made of a zircon-titanium material, and that the internal diameter of the fibers of the filter was limited to up to 3mm to reduce wall shear stress (thereby enhancing the viability of the cultured bacteria). The Patent Court upheld the corrected claims on appeal in 2016, but the challenger initiated a separate challenge to the validity of the correction itself, which resulted in the Patent Court (through a different judge panel) ultimately issuing another ruling in 2018 that the corrected claims lacked inventiveness. Meanwhile, the 2016 Patent Court decision was appealed to the Supreme Court, which finally invalidated the patent and largely followed the reasoning of the 2018 Patent Court decision.
	The 2016 Patent Court decision focused its validity analysis on whether the prior art disclosed the use of a zircon-titanium membrane material to reduce wall shear stress in bioreactors and thereby enhance viability of bacteria. Since that panel concluded that the prior art recognized the problem of membrane fouling but not wall shear stress in bioreactors, that it was not known that wall shear stress was relevant to bacteria viability, and that the prior art did not specifically recognize the use of zircon-titanium membranes in bioreactors or that such material would reduce wall shear stress, the panel concluded that the patent was inventive.
	The 2018 Patent Court decision, on the other hand, broadly concluded that most of the individual elements and effects of the claimed bioreactor were generally known in the art or would have been inherently addressed by solving known problems (e.g., that zircon-titanium membranes are a commonly-used material for ceramic membranes in bio-related industries, even if not specifically in bioreactors; and that the main cause of membrane fouling is cell debris, and therefore reducing cell debris intrinsically reduces wall shear stress). The 2018 panel thus concluded that the only new element in the invention for validity purposes was the numerical limitation of the membrane fibers to a 3mm diameter (the prior art disclosed diameters of 0.3-1mm, which involved problems with wall shear stress), but that the limitation of 3mm had no real critical significance since one of ordinary skill knowing the problem of wall shear stress would have had naturally considered increasing the diameter to deal with the issue. The Supreme Court, in addition to affirming the 2018 Patent Court decision, noted that there was no data or detailed explanation in the specification regarding the correlation between different membrane materials and wall shear stress (and therefore no support for the proposition that zircon-titanium membranes are particularly useful for reducing wall shear stress, as claimed).
	The reasoning of the Supreme Court (and the 2018 Patent Court) is problematic because it appears to begin with the elements of the invention, then mechanically compares them to the prior art to isolate the fiber diameter element as a basis for characterizing the invention as a "numerical limitation" invention, rather than considering the disclosures of the prior art references themselves and determining whether one of ordinary skill would have been motivated to conceive the combination of elements in the invention, including the numerical limitation. None of the cited references disclosed or suggested the use of a ceramic membrane specifically for bacteria production (as opposed to water purification or food sterilization), yet the Supreme Court appears to have simply ignored this gap and required the patentee to demonstrate a special technical significance to the specific claimed diameter of membrane fibers beyond the application of ceramic membranes to this area of technology.
	Unfortunately, this case was highlighted for publication by the Supreme Court itself, which suggests that the Supreme Court will continue this type of selective analysis of inventions containing a numerical limitation as a technical feature. Thus, where possible, patent applicants in Korea should seek to rely on features or effects relating to elements other than or in addition to numerical ranges of values to distinguish their inventions from the prior art.
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