Evidence Collection: A Guide for Those Facing Patent Infringement in Japan

Are you facing challenges in gathering evidence to support your claims of patent infringement? Or are the difficulties of evidence collection discouraging you from pursuing legal action?

To address these concerns, we have prepared a Q&A guide outlining common questions about evidence collection in patent infringement cases in Japan.

I am having trouble collecting evidence to prove infringement. Does Japan have a discovery process equivalent to that in the United States?

No, Japan does not have a discovery process equivalent to that in the United States, where parties can compel the opposing side to disclose relevant information before trial under the Federal Rules of Civil Procedure (FRCP).

However, under the Japanese Patent Act, Japan has several legal measures that can help parties collect the necessary evidence. The key measures are described in the section below.

Legal Measures for Evidence Collection

Document Submission Order (Japanese Patent Act, Article 105)

The court may, upon a party’s motion, order the holder of a document to submit it if the document is necessary to prove infringement or calculate damages, unless the holder has a legitimate reason for refusal.

Key Point

It is rare for a court to issue an order to submit documents specifically for proving infringement. However, once the court has disclosed its preliminary judgment on infringement, obtaining an order to submit documents for calculating damages becomes relatively easier.

Investigation Order System (Article 105-2-1~9)

If it is unclear whether the alleged infringer is, for example, using the patented method to manufacture products, the court may, upon a party’s motion, order an expert to investigate the alleged infringement. The expert may enter the relevant facilities, request documents, and conduct inquiries to examine potential infringement.

This system is also expected to apply to software patents and patents on large-scale manufacturing equipment that are not easily obtainable on the market.

Key Point

Introduced relatively recently (effective from October 1, 2020), this system has not yet been utilized in practice. For example, in one case (Reiwa 1 (Wa) 30991), the court dismissed a motion for an investigation order, ruling that the plaintiff’s patent should be invalidated.

Because compliance with an investigation order places a significant burden on the opposing party, the requirements for using this system are stringent. However, as this system becomes more established, the likelihood of issuing such orders may increase. If you are sued for infringement, be aware of the potential for an investigation order and prepare your litigation strategy accordingly.

Proceedings for Calling for Third-Party Opinions (Article 105-2-11)

Upon a party’s motion, the court may, if necessary, solicit public opinions on matters relevant to its judgment. These opinions can be used as evidence. These opinions can be used as evidence. This system was introduced with the amended Patent Act, which took effect in April 2022.

Key Point

This system is similar to amicus curiae briefs in the United States, and was first applied in a case (Reiwa 4 (Ne) No. 10046).

The scope of third-party opinions is broad and may include legal issues, established rules, business practices, and actual business conditions. If such information supports your claims, consider using this system. However, be aware that the content can be unpredictable and may contain unfavorable information that challenges your position.

Special Provisions on Burden of Proof

In addition to the above systems, the Japanese Patent Act provides specific measures to ease the burden of proving infringement:

Obligation to Clarify Specific Circumstances (Article 104-2)

If the defendant denies the alleged infringing act, they are legally obligated to clarify the specific mode of their actions.

Key Point

The defendant may be exempt from this obligation if a legitimate reason exists. Moreover, since this provision does not prescribe any penalties for non-compliance, the defendant may choose not to disclose the required information. In such cases, an order to submit documents under Article 105 may become necessary.

Presumption of Production Process (Article 104)

If a product produced by a patented method was not publicly known in Japan before the patent application, it is presumed that identical products were produced by that method. This presumption shifts the burden of proof to the defendant.

Remaining Challenges in Evidence Collection

Japan’s Code of Civil Procedure also includes specific provisions for evidence collection. However, since much of the evidence in patent infringement lawsuits is held by the defendant, obtaining the necessary evidence can still be a significant challenge.

How We Can Support

Our law firm has attorneys with extensive research experience who develop effective strategies for collecting evidence in patent infringement cases. Leveraging our strong background in technical evaluation and scientific data analysis, we provide comprehensive litigation support to achieve the best possible outcome for your case.

For more information or inquiries, please do not hesitate to contact us. Initial consultations are free, and we will clearly explain any fees before proceeding. We are here to support you in taking the first step to protect your patent rights.

(Last Update: September 16, 2024)

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