Tokyo District Court, Reiwa 5 (Wa) 70619 [Apparatus for measuring the difference between port and starboard vessel drafts] <Presiding Judge Nakashima>
Updated: 4 days ago
Article information
Article type: Case note
Category: Patents
Topics: Patent corrections, Employee inventions
First published on this website: October 2, 2026
Case number (as stated in the source): Tokyo District Court, Reiwa 5 (Wa) 70619
Display and classification checked: October 2, 2026 (not a re-review of the legal analysis)
Tokyo District Court, Reiwa 5 (Wa) 70619 [Apparatus for measuring the difference between port and starboard vessel drafts] <Presiding Judge Nakashima>
The plaintiff made a draft-difference measurement invention while employed by the company.
⇒ The company applied, but the application was refused and no patent was granted.
First and second lawsuits: The plaintiff asserted ownership of the right to obtain a patent. The courts found an employee invention; the plaintiff lost.
⇒ The plaintiff then applied individually and obtained the patent at issue.
Third lawsuit: The plaintiff sued the company for infringement, but lost because this was an employee invention and the application had been filed without entitlement.
Fourth lawsuit: Claim for remuneration for the employee invention.
⇒ The plaintiff lost because the company obtained no benefit.
Fifth lawsuit, this case: The plaintiff alleged loss because the company had lied in earlier proceedings. The company counterclaimed for wrongful litigation, alleging relitigation.
The judgment
• No finding that the company had lied in court.
• The plaintiff voluntarily paid patent-maintenance costs, including annuities; those costs were not attributable to the company.
★ Why it was an employee invention
The company had been commissioned by its parent to improve draft surveys, so the invention fell within its business.
The plaintiff bought components at company expense and conducted tests as an employee.
Company's counterclaim
Although some of the plaintiff's declaratory claims conflicted with earlier judgments, the earlier findings were merely reasoning within infringement proceedings and similar determinations.
⇒ The right of access to courts is important. Bringing this action could not be characterized as an unlawful act manifestly lacking justification.
Original article: https://lnkd.in/erAYKFcR
Related cases and materials
Update and correction history
Substantive corrections and supplements are recorded separately from classification, related-article, and display maintenance.
October 2, 2026: First publication of the author's LinkedIn text. Article type, classification, issue tags, source, and consultation guide were added.
Consultation and inquiries
October 2, 2026: Updated topic tags.
2026-10-13: aligned related-article, topic-guide, and other managed links with the articles’ published URLs. The original article text was not changed.
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