Tokyo District Court, Reiwa 6 (Wa) 4142 [Portable information communication device] <Presiding Judge Kokubu>
Updated: 3 hours ago
Article information
Article type: Case note
Categories: Patents
Main topics: Litigation procedure / Damages
First published on this website: October 1, 2026
Case reference (as stated in the original): Reiwa 6 (Wa) 4142
Display and classification checked: October 1, 2026 (not a revalidation of the legal analysis)
Tokyo District Court, Reiwa 6 (Wa) 4142 [Portable information communication device] <Presiding Judge Kokubu>
= Tokyo District Court, Reiwa 6 (Wa) 70083
* A separate action claimed consumption-tax-equivalent amounts not claimed in the earlier proceedings, but was dismissed as inadmissible for violating good faith.
The plaintiff argued: ① the tax-equivalent amounts had not been examined earlier, so this was not relitigation; ② the tax loss had a different cause from the royalty loss; and ③ the tax rate would be fixed when the judgment became final, making an earlier claim difficult.
⇒ The court noted that claims and awards of consumption-tax-equivalent amounts as part of damages or losses are not uncommon in patent infringement litigation. The plaintiff could not be said to have been unable to recognize this practice. The amount was readily calculable by multiplying the royalty-equivalent amount by the then-applicable tax rate (already 10% at the close of oral argument here). Claiming it together with royalties in the two earlier actions was therefore not difficult. Nor had the plaintiff expressly limited the claims to royalties or indicated that tax was excluded from examination.
⇒ The plaintiff could have submitted the entire loss, including tax, for examination, or expressly excluded the tax portion, but deliberately did neither and lost on a partial claim. The remaining claim would defeat the defendant's reasonable expectation that the dispute over the entire debt had been resolved and impose the burden of defending twice.
No special circumstances existed. The court therefore held the action impermissible under procedural good faith and dismissed it as inadmissible without reaching the merits of unjust enrichment.
(Excerpt from the judgment — English translation; other excerpts omitted to fit the post limit)
“In light of the foregoing, it is appropriate to construe that a plaintiff who loses an action asserting a quantitatively partial claim for a monetary debt is, absent special circumstances, barred by good faith from bringing an action claiming the remainder.”
(Supreme Court, Heisei 9 (O) 849, Second Petty Bench judgment of June 12, 1998, Minshu Vol. 52, No. 4, p. 1147.)
Original article: https://lnkd.in/gy7GNFBJ
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Substantive corrections and additions are recorded separately from classification, related links and display changes.
October 1, 2026: First publication of the author's original LinkedIn text on this website. Article type, categories, topic tags, sources and consultation navigation added.
2026-10-01 | Display maintenance: added case references stated in the original or language-alternate metadata; not a revalidation of legal analysis.
2026-10-01 | Name notation: replaced verified Japanese-script personal names with Roman-letter forms in this English article and its navigation. Legal analysis and original publication date unchanged.
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