Japanese Patent FAQs

Enforcement

Update 2023.3.9

Q.How long after the expiration of a Japanese patent can a patent owner still bring an infringement suit?

A patent owner can bring an infringement suit within three years from the time when he/she learns of the infringement and identifies the infringer. Additionally, the right to bring an infringement suit expires twenty years after the infringement begins.

Q.Are there any differences procedurally when an infringement suit is commenced after the expiration of a patent?

After the expiration of a patent, only damages can be demanded. That is, you cannot obtain an injunction after expiration.

Q.Does Japan recognize a provisional right to early damages before the patent is granted?

Yes. Regarding pre-grant damages, when a patent is granted, the patentee may exercise the right to demand compensation for an infringer’s acts carried out from the date the patent application was published in Japan to when the application was granted.

Q.What are the requirements for getting provisional rights?

To claim compensation for an infringer’s acts carried out before the issuance of the patent, a warning letter stating the contents of the claimed invention must be sent to an infringer while the application is pending and after the publication of the application.

Q.How much is the compensation for pre-grant damages (provisional right)?

The compensation will be the amount of royalties the patentee would have earned from the use of the claimed invention. It is not possible to claim lost profits.

Q.Is it possible to obtain an injunction to prohibit an infringer’s activity based on provisional rights?

No. The patent owner cannot enjoin an infringer from the activity based on provisional rights.

Q.How long can the patentee take advantage of provisional rights?

If a warning letter is sent to an infringer prior to the issuance of the patent, the patentee can seek compensation for provisional rights as late as three years from the date of registration of the patent.

Q.Is it necessary to send a warning letter to an infringer? Is there any other way to take advantage of provisional rights?

If the patentee can prove that the infringer intentionally used the invention(s) described in the published patent application of the Patentee, it is possible to take advantage of provisional rights. In that case, the patentee can seek compensation for provisional rights as late as 20 years from the date of registration of the patent, and also within three years from the date of sending the warning letter to the infringer. We recommend that a warning letter be sent to the infringer prior to the issuance of the patent as it will likely be very difficult to prove that the usage by the infringer was intentional.

Q.From when can a Japanese patent be enforced?

The patentee can begin enforcing a patent against infringers when the patent is registered at the JPO. If you would like to enforce a patent after the payment of the registration fee but before the certificate of patent is issued, it is recommended to perform a daily check of the patent’s status on the JPO’s website to determine when has been registered.

FAQs