“Exception to Lack of Novelty” in Japanese Applications Claiming Paris Convention Priority

One source of confusion for U.S. applicants is terminology. In the United States, product appearance is protected by a design patent, and a design patent is treated as part of the broader patent system. In Japan, by contrast, patents and designs are governed by separate statutes and separate procedural systems. This distinction is important because the analysis of the exception to lack of novelty is not the same for the two systems.

Many foreign applicants tend to assume that, if they made their first filing in their home country within that country’s grace period, they can later file in Japan and still rely on the Japanese exception to lack of novelty. That assumption is dangerous. Under Japanese law, the relevant timing requirements must be satisfied separately under the Japanese system applicable to the particular right in question. In the case of designs, the Japanese design application must be filed within 12 months from the date on which novelty was lost, and the required declaration and supporting evidence must also be submitted.

In the design context, there is a particularly important trap for U.S. applicants. Under the Paris Convention, the priority period for designs is six months. In my experience, it is rare for professional practitioners to misunderstand the priority period itself. However, where an applicant seeks to rely on the exception to lack of novelty, filing within the priority period alone is not sufficient. First, the Japanese design application must be filed within 12 months from the date on which novelty was lost. Second, that same Japanese application must also be filed within the six-month Paris priority period counted from the filing date of the basic application. Satisfying only one of these requirements is not enough.

Accordingly, even if a U.S. design patent application was filed in a timely manner, that alone does not secure Japan. Even where the U.S. filing was made promptly after the date on which novelty was lost, the applicant may still lose the benefit of the Japanese exception to lack of novelty for designs if the Japanese design application is filed too late. In practice, Japanese design practice requires a double deadline check: “within 12 months from the date on which novelty was lost” and “within 6 months from the filing date of the basic application.”

Japanese patent practice is different. Under the Paris Convention, the priority period for patents is 12 months. In addition, under JPO practice relating to Article 30 of the Patent Act, when determining whether the application was filed within one year from the date on which novelty was lost, ordinary Paris-priority applications are distinguished from PCT international applications. In an ordinary Paris-priority case, the relevant date is the Japanese filing date. By contrast, in the case of a PCT international application, the relevant date is the international filing date.

This distinction can be outcome-determinative. If the applicant first files an ordinary foreign patent application and then files in Japan claiming Paris Convention priority, the Japanese exception to lack of novelty may be unavailable unless the Japanese filing date itself falls within 12 months from the date on which novelty was lost. By contrast, if the first filing is a PCT international application, protection in Japan may still be preserved so long as the international filing date falls within 12 months from the date on which novelty was lost and the priority claim is validly made. In this sense, the PCT patent route may preserve Japanese options that would otherwise be lost under the ordinary Paris-priority route.

U.S. applicants should not allow the familiar U.S. concept of a design patent to mislead them into thinking that designs and patents are treated in the same way in Japan. For Japanese design applications, even where there is an earlier U.S. design patent application, the Japanese filing must satisfy both the 12-month period for the exception to lack of novelty and the six-month Paris priority period. By contrast, the analysis is different for Japanese patent applications, and where a PCT application is used, the international filing date becomes the controlling date, creating a real possibility of preserving rights.

For companies that disclose products on social media, YouTube, at trade shows, or through early launch campaigns, this is not merely a technical issue. Missing the relevant deadline may result in the complete loss of protection in Japan. The safest rule is simple: once novelty has been lost by disclosure or otherwise, Japan must be analyzed immediately as a separate issue, and Japanese design and patent options must be considered separately.