A Recent IP High Court Ruling on Numerical Limitations
The Japanese Patent Office Examination Guidelines state that for an invention to have an inventive step over the prior art when the distinguishing feature of the present invention includes a numerical limitation, the invention needs to yield a prominent, unexpected effect throughout the entire range of the numerical limitation. Furthermore, the original specification as filed must fully support this effect, and the applicant is not allowed to supplement the disclosure with additional evidence.
However, usually the unexpected effect over the prior is not sufficiently supported in the specification. As a result, invalidation of this kind of patent has been relatively easy if new prior art can be brought before the JPO.
Recently the IP High Court has become more patent friendly. In keeping with this trend, the IP High Court did not consider whether the distinctive numerical limitation yielded the prominent unexpected effect when, on November 27, 2008, it found that the patent-in-suit should be maintained, overruling the JPO. In this case, the patented invention was directed to a process for creating a mud slurry by mixing construction soil from, for example, drilling during subway construction, with water, cement and so forth. The claimed process is different from the prior art in that the soil that is the main constituent of the slurry has been processed to contain approximately 55-65% water. Although the prior art disclosed different water content percentages for the soil, the IP High Court found that the prior art itself did not suggest the idea of processing the main constituent to the appropriate condition (a water content of approximately 55-65%), and therefore the patented invention has an inventive step over the cited prior art.