Evidence identification and screening in patent invalidation proceedings-Case

Lawyer’s Insights: In patent infringement litigation, the key to resolving the issue for the defendant often lies in whether they can invalidate the plaintiff’s patent through a patent invalidation request, thus achieving a decisive victory. The success of a patent invalidation request hinges on evidence retrieval. For most patent invalidation cases, the availability of evidence is crucial; finding good evidence greatly increases the chances of invalidation. Conversely, the patentee can maintain the validity of their patent. However, finding valid evidence is often extremely difficult, a key issue being the lack of recognition of valid evidence. Many times, the searcher sees usable evidence but fails to recognize it, letting good evidence slip by.

In this case, the difficulty in retrieving the target patent lies in the description of “a groove (10) formed along its periphery inside the casing (3), the groove (10) having a continuously increasing radius in the circumferential direction, extending to the outlet (8), which is tangentially positioned as a direct continuation of the groove (10).” In the first two invalidation requests in this case, no suitable evidence was found, thus failing to resolve the issue. In fact, the key evidence used in the third invalidation proceedings was not difficult to find. However, the inventive concept of the evidence itself was completely different from the target patent, and its specification lacked keywords linking to the target technical features. Usable technical features required professional lawyers to identify them from the accompanying drawings. Previous searchers had ignored or overlooked this evidence. At this point, lawyer Yu Chunbo’s extensive engineering experience proved invaluable; he astutely identified the direct and unambiguously disclosed technical features in the accompanying drawings.