What Is the Evidence Value of Private Documents In Patent Opposition Cases & Patent Invalidation Trial Cases?

In PTO cases, a problem is evaluating the evidence value of private documents for patent invalidation or opposition in Patent litigation.

In civil cases, many kinds of private documents may be submitted to the court as evidence. For example, in patent cases, patent opposition trials, or patent invalidation trial cases, if a private document such as an in-house document is submitted as a publicly known document that denies patentability, the evidential capacity is considered in the court. A problem is evaluating the evidence value of private documents in Patent litigation.

In general civil cases, judicial precedents show that, in many cases, even handwritten memos, for example, are basically accepted as evidence – ie. their admissibility as evidence is not denied.

On the other hand, in the case of the Patent Office cases, opposition trials or invalidation trials, the handling of such evidence is slightly different. In the case of a patent, for example, such evidence is submitted to the Patent Office at the trial court for patent invalidation or opposition, and it becomes a problem as to the grounds for opposition, cancellation or invalidation to be proven.

Most of the grounds for invalidation and opposition relate to novelty and/or inventive step. Furthermore, when detailed, grounds are divided into public knowledge, publicly known to be used, and described in a publication. From my own experience, the most difficult evidence to be accepted by the PTO is the evidence on “publicly known to be used” even in Japan, and especially, in a foreign country. 

For example, in a certain case in which we were involved, a photograph of a kind of technology similar to an invention being implemented in a foreign country was submitted as evidence. The date of shooting of the photo is printed on the photograph itself. However, corroborative evidence showing the ground of “publicly known to be worked” is required, and whether or not it is comprehensively eligible as evidence to prove “publicly known to be worked” must be examined.

Unlike general judicial court proceedings, proceedings at the Patent Office are based on ex officio proceedings, so the panel will determine whether or not the evidence is suitable for proving “publicly known to be worked”. In our case, interrogations will be held, and the final decision that the evidence should be disregarded was made by a panel of judges. This point is different from judicial proceedings based on the principles of the court and the PTO.

At Kimura & Partners, we focus on supporting domestic and foreign companies, especially SMEs, register and defend their IP in what we call the IP battleground.  As to this article… A problem is evaluating the evidence value of private documents in Patent litigation. The solution requires a good understanding of the PTO process.

By Takaaki Kimura

Managing Partner and Patent Attorney with over thirty-five years of IP law experience.