1. Introduction
On 18 December 2025, 452 plaintiffs filed a tort case, suing Japanese government for damages incurred due to its inadequate climate change measures. According to the complaint, they seek 1,000 yen in compensation per person as a part of damages suffered by each plaintiff.1
Prior to this case, Japan has observed five climate cases in Japan, four of which sought to halt the construction or operation of coal-fired power plants (CFPPs) one sought emission reduction from thermal power plants.2 As of this writing (January 2026), four of these cases were concluded with dismissal, with one case remaining in the first instance of the civil proceeding. This case is therefore the first case to claim state’s tort liability, incorporating several novel elements not seen in the previous five cases. Moreover, it is also the first case in Japan filed after the advisory opinion on obligation of states in respect to climate change, issued by International Court of Justice (ICJ) in July 2025. The complaint explicitly references this opinion to justify their argument. As of writing this commentary, no information regarding the date and time of the first hearing has been publicly disclosed.
This paper attempts to locate this case within the context of Japan’s climate litigation. It then briefly examines the potential and challenges of this case.
Below, section 2 introduces the background and history of past climate cases in Japan. Section 3 introduces this case, focusing on the content of the complaint. Section 4 examines potential and challenges this case connotes, by comparing this case with precedent ones with particular focus on the legal issues. Sections 5 concludes.
2. Background: The Trajectory of Climate Litigation in Japan
2.1 Japan’s Energy Policy and Greenhouse Gas Emissions
Following the Fukushima Daiichi Nuclear Power Plant accident caused by the Great East Japan Earthquake in March 2011, all nuclear power plants in Japan were shut down. In response, the government adopted a policy to substantially loosen requirements in environmental impact assessment (EIA) procedures for the construction of thermal power plants, aiming to expedite EIA procedures to ensure a stable power supply.
Under this policy, the government issued guidelines for simplifying the EIA procedure for thermal power plant replacement projects in 2012.3 Additionally in 2013 the government also issued the Director-General’s Summary, which significantly loosened the criteria for review.4 These issuances triggered a construction rush of CFPPs, resulting in 159 facilities in operation with one more planned in Japan at the time of writing.5 Consequently, Japan’s greenhouse gas (GHG) share accounted for 2.0% of global emissions in 2024, making it the eighth largest emitter in the world.6 The power sector accounts for a significant portion, with approximately 90% of energy industry that accounts for 43% of the national total CO2 emissions.7
2.2 Climate Litigation in Japan
As mentioned above, Japan’s five past climate lawsuits all sought to halt the construction or operation of thermal power plants, against that construction rush and subsequent increase of CO2 emissions (Table 1).8 Three civil cases sued private thermal power plants as defendants, while two administrative cases sued the government to annul the national approval for the plants’ construction. In the former, the plaintiffs argued that their right to be free from the adverse effects of climate change had been violated, which the courts did not recognize. The courts also denied any causal link between the alleged rights violations and the defendants’ emissions. In the administrative cases, the court denied the plaintiffs’ standing. Moreover, it denied the illegality of the national government’s disposition approving the plant’s construction, reasoning that it was made within the scope of administrative discretion.
Table 1
Past Five Climate Cases in Japan.
| YEAR DECIDED | COURT | CAUSE OF ACTION | PROCEDURE AND EVIDENCE | REMEDIES AND RULING |
|---|---|---|---|---|
| 2020, 2021 | Sendai District Court Sendai High Court | Injunction of operation of CFPPs based on the Human Rights by 124 residents | Civil Litigation (injunction) | 1st instance: Dismissed Court of Appeal: Dismissed |
| 2023, 2025 | Kobe District Court Osaka High Court | Injunction of construction & operation of CFPPs based on traditional Human Rights and the Human Rights in the context of climate change by 40 residents | Civil Litigation (injunction) | 1st instance: Dismissed Court of Appeal: Dismissed |
| 2021, 2022, 2023 | Osaka District Court Osaka High Court Supreme court | Revocation of the final notice of EIA admittance conducted for CFPP construction by 12 residents | Administrative Litigation | 1st instance: Dismissed Court of Appeal: Dismissed Supreme Court: petition for acceptance of appeal dismissed |
| 2023, 2024 | Tokyo District Court Tokyo High Court Supreme Court | Revocation of the final notice of EIA admittance conducted for CFPP construction by 45 residents | Administrative Litigation | 1st instance: Dismissed Court of Appeal: Dismissed Supreme Court: petition for acceptance of appeal dismissed |
| (Not yet) | Nagoya District Court | Partial Injunction of emissions based on civil tort by 16 youth | Civil Litigation (injunction) | (Not yet) |
3. Overview of This Case
3.1 Background
On 14 July 2025, the lead attorney posted a statement of initiation of the case on his social media, which was an unprecedented manner of announcing a case prior to its filing.9 Meanwhile the official website was launched soon thereafter, with the hash-tagged subtitle “We gave it a try to file a case to protect the Earth”.10 These are examples of announcements for the case, led by the attorney’s team. Anyone can become a plaintiff by submitting the letter available on the website, and paying 1,000 yen participation fee. They also involved various prominent figures as members or supporters, listing their names on the website. Such effort resulted in 452 individuals becoming plaintiffs. Additionally, a summary of the complaint (14 pages) was published on the website, and the full complaint was similarly published just after filing. Furthermore, the attorneys plan an additional filing in February 2026 with over 450 plaintiffs.
3.2 Summary of the Complaint
The complaint consists of six chapters. Following the case overview (chapter 1), three chapters establish the factual background: the mechanisms of climate change and required countermeasures (chapter 2), and the domestic and international legal frameworks surrounding climate change (chapter 3).11 From chapter 4, the corresponding facts to the requirements of Article 1, Paragraph 1 of the State Redress Act, which form the basis for the claims against the state’s tortious conduct, are presented.12 This act is a special law concerning tort liability for the state as a tortfeasor.13
3.2.1 Rights Infringement Due to Climate Change (Chapter 4)
Chapter 4 of the complaint lists infringed rights, categorizing them into the following two types.
The first is the right that is actually being infringed. Specifically, this includes the right to life and health (article 13 of the Constitution, article 6(1) of the International Covenant on Civil and Political Rights, article 12(1) of the International Covenant on Economic, Social and Cultural Rights), the following rights speculated in the Convention on the Rights of the Child: article 6 (right to growth and development), article 19 (right to protection from violence), article 24 (right to enjoy health, article 28 (right to education), article 31 (right to play), and following constitutional rights: freedom of business (article 22, Paragraph 1), property rights (article 29, paragraph 1), and environmental rights (not explicitly stated in the Constitution but derived through interpretation of articles 13 and 25).14
The second is the right to peaceful life that has been recognized in precedents as a content of personality rights.15 In three past climate civil cases, the right to enjoy a stable climate, or the right to live healthily and happily in a world without temperature rises exceeding 5°C, were asserted as infringed rights, as part of the right to peaceful life. Notably, the first-instance judgment in the Kobe civil lawsuit generally recognized that the effects of global warming could constitute an infringement of the right to peaceful life.16
3.2.2 State Liability (Chapter 5)
Here, the State’s obligation is identified as reduction of GHG emissions necessary to achieve the 1.5°C target, the primary temperature goal agreed upon by the parties to limit the global average temperature rise under the Paris Agreement. Next, the complaint argues that Japan’s current targets fall short both in terms of numerical targets and in adopting a linear reduction pathway. Public official who set these current targets are deemed to have violated the norms governing official duties, given the gravity of the consequences; human rights violations caused by climate change. Furthermore, the legislative inaction of Members of the National Diet, the legislative body, who failed to enact the legislative measures necessary to achieve the 1.5°C target over the long term is deemed unlawful. Then, 12 specific examples are cited as occurred damages. It includes personal experiences of heatstroke, restrictions on children’s activities, additional economic burdens, and damage to primary industries. They assert that those damages account for more than 1,000 yen in each.
3.3 Actions After Filing
After filing the case, the plaintiffs’ attorneys continue to recruit additional plaintiffs for a second and subsequent lawsuits, holding regular online information sessions. These sessions include explanations by the lead attorney about the background and significance of this case, followed by time for questions from participants.17 Additionally, they organize collaborative events with the past climate cases, to expand supporters.18
4. Discussion
This section firstly compares this case with previous climate cases. Then it explores its potential and challenges.
4.1 Comparison with Previous Cases
4.1.1 Target of Litigation Activities
First, activities of the attorney’s team as a whole appear to prioritize helping the general public understand the significance of the case, rather than persuading the judge. In the past five cases, the plaintiffs and attorneys emphasized continuity with traditional pollution lawsuits in Japan. They developed legal arguments that promoted judges to utilize existing legal theories and current laws while incorporating novel elements specific to climate change through interpretation, without significantly deviating from established judicial practice. One example can be observed in the Kobe civil case, where the plaintiffs and attorneys cited a precedent from past air pollution litigation that established joint tort liability among multiple factories as emission sources and apportioned the compensation each factory owed based on its contribution to emissions.19 They applied this established legal theory to Kobe’s case to justify their claim to oblige defendant CFPPs to halt partial operation. Additionally, the action for the judicial review of an administrative disposition (Article 3, Paragraph 1 of the Administrative Case Litigation Act20), the adopted legal proceedings in two administrative cases, has been known as one of the typical provisions frequently invoked in conventional pollution lawsuits.
In contrast, this case appears to employ relatively straightforward language in the complaint with various figures. This format seems to be designed to allow even non-specialists in climate science to grasp the its mechanisms to a certain extent. A 14-page summary is also published on the official website for readability by the general public, which the previous five cases did not provide. Furthermore, the legal framework of the state redress claim adopts a simple schema compared to the past cases: citizens suffer damages due to the state’s inadequate climate policies. This makes intuitive understanding accessible to ordinary citizens. The attorneys could adopt this legal framework possibly because the ICJ’s advisory opinion in July 202521 clarified the state’s obligations regarding climate change, which had been unclear when the previous five cases were filed.22
4.1.2 Emphasis on Accessibility for Citizens
Second, various efforts made this lawsuit accessible to citizens. Notably, the requirement to become a plaintiff was novel. In contrast to this, in past climate lawsuits, plaintiffs were selected as someone possessing the qualities necessary to endure a protracted legal battle, as a strategy to win the case.
Moreover, regarding damages caused by climate change, the official website provides a checklist titled “What damages have you experienced?”. This aims to raise awareness that diverse events occurring in the daily lives of ordinary citizens are caused by climate change, thereby encouraging them to become plaintiffs. Some examples include: increased costs from installing air conditioners and running them constantly; outdoor work becoming impossible during summer daytime hours; and homes or offices damaged by typhoons, heavy rain, wind, or landslides. These are events many citizens can likely relate to or have experienced.
Furthermore, in Japan where the general perception remains that filing a lawsuit is not a casual activity,23 the website innovatively frames case filing as accessible and meaningful. Proof of this includes its hash-tagged subtitle of “We gave it a try to file a case to protect the Earth” in its website, as well as the involvement of prominent figures active in diverse social issues as members and supporters.
4.2 Potential and Challenges
Regarding potential, this case may generate a revolutionary impact while building upon the precedence achieved by the five previous cases. It apparently aims not only to obtain a victory in court itself but also to use the litigation as a catalyst to generate a wave of social movement, thereby building national momentum to advance Japan’s climate change policies. In this regard, Japan has also seen the use of public interest litigation: cases that, while raising expectations that disputes and demands involving policy criticism, which would ideally be resolved at the legislative or administrative level, could be addressed within the institutional framework of judiciary.24 This case appears to aim for the ultimate utilization of this approach, as the criticism of policy itself seems central to the purpose of the lawsuit.
As for challenges, sustaining unity of the plaintiff group through the long-term litigation process of climate case may face several hurdles. Easiness of becoming a plaintiff simultaneously implies that the group includes plaintiffs who may not have fully prepared for the long-term commitment required. In this regard, literature has shown that the significance and purpose of becoming a plaintiff in a lawsuit are diverse.25 Prospected significant procedural decisions at several stages, including the consolidation of the second filed case already announced by the attorneys, possible settlement negotiations with the government, and amendments or partial withdrawals of claims. The manner in which the attorneys consolidate and lead the plaintiffs during these critical moments will be a key challenge ahead.
5. Conclusion
This paper introduced one of the more recent Climate Justice cases in Japan. It outlined the background of climate litigation in Japan, the circumstances leading to this lawsuit’s filing, and the content detailed in the complaint. It then compared this case with previous climate lawsuits, to identify its potential and challenges that may arise. This case, which differs from the previous five cases in various respects and includes a second filing scheduled for February 2026, has the potential to bring significant changes to the development of climate litigation in Japan, drawing continued attention.
Notes
[1] Kikou Seigi Sosho [Climate Justice Case] (in Japanese) <https://climate-j.com/> accessed 6 March 2026.
[2] According to the Climate Litigation Database operated by the Sabin Center for Climate Change Law, the definition of climate litigation refers to cases brought before judicial bodies and climate change law, policy, and/or science must be a material issue of law or fact in the case <https://www.climatecasechart.com/methodology> accessed 6 March 2026. This paper identifies climate litigation in Japan based on this definition. As a report on Japanese climate litigation including summaries of these five cases: Masako Ichihara et al, ‘Global Perspectives on Corporate Climate Legal Tactics: Japan National Report’, British Institute of International Comparative Law.
[3] The Guideline on simplification of Environmental Impact Assessment for Replaced Power Plants <https://www.meti.go.jp/policy/safety_security/industrial_safety/sangyo/electric/files/kankyo_assessment/kaiteigonogaidorain009_02_00.pdf> accessed 6 March 2026.
[4] Summary of the Director-General Meeting concerning Tepco’s Thermal Power Source Bidding <https://www.climatecasechart.com/> accessed 6 March 2026.
[5] Beyond Coal Japan <https://beyond-coal.jp/en/map-and-data/> accessed 6 March 2026.
[6] Crippa, M.et al., ‘GHG emissions of all world countries – 2025 Report’ [2025] Publications Office of the European Union, Luxembourg, p.11 <https://data.europa.eu/doi/10.2760/9816914, JRC143227> accessed 6 March 2026.
[7] Ministry of Environment, ‘Greenhouse Gas Emissions and Absorption in FY 2023’ (in Japanese) <https://www.env.go.jp/content/000357136.pdf> accessed 6 March 2026.
[8] English summaries of cases are available at Sabin Center’s database (supra note 2, <https://www.climatecasechart.com/geographies/japan>) accessed 6 March 2026.
[9] Facebook profile of attorney Akihiro Shima, posted on 14 July 2025 <https://www.facebook.com/story.php?story_fbid=9889324827863081&id=100003569862957&mibextid=wwXIfr&rdid=kF6jH7igLw67NN4B#> accessed 6 March 2026.
[10] Climate Justice Case <https://climate-j.com/> accessed 6 March 2026.
[11] Complaint (in Japanese) <https://climate-j.com/wp-content/themes/blankslate-child/pdf/complaint-1218.pdf > accessed 6 March 2026.
[12] State Redress Act, Article 1(1).
When a public employee who exercises the public authority of the State or of a public entity has, in the course of their duties, unlawfully caused loss or damage to another person intentionally or negligently, the State or public entity assumes the responsibility to compensate therefor.
Official translation available at https://www.japaneselawtranslation.go.jp/ja/laws/view/3785> accessed 6 March 2026.
[13] Shiomi Y, *Library Hougaku Kihon Kogi: Saiken Kakuron II: Fuhoukoui hou [Basic Lecture of Law: Law of Contract II: Tort Law] (in Japanese) (Shinseisha, p156–7, 2021).
[15] Personal rights lack explicit statutory provisions. The court has not so far identified the article from which they are derived. The prevailing academic view holds that Article 13 of the Constitution is the basis. Colin P.A. Jones ed, The Annotated Constitution of Japan: A Handbook, pp: 61–2. Routledge, 2023.
[18] A launching event was held on 27 January 2026. Information available at <https://climate-j.com/event/144/> accessed 6 March 2026.
[19] Tsu Chiho Saibansho Yokkaichi Shibu [Tsu Dist. Ct. Yokkaichi Branch] Jul.24.1972. Hanrei Jihou [Hanji] 672,30.
[20] Administrative Case Litigation Act, Article 3. Official translation is available at <https://www.japaneselawtranslation.go.jp/ja/laws/view/3781 > accessed 6 March 2026.
[22] In Youth Climate Case, this advisory opinion is cited in documents submitted by plaintiffs’ attorneys after its issuance <https://youth4cj.jp/en/documents/> accessed 6 March 2026.
[23] Ginsburg, T., & Hoetker, G, ‘The unreluctant litigant? An empirical analysis of Japan’s turn to litigation’, The Journal of Legal Studies, 35(1), 31–59, 2006.
[24] Shigeaki Tanaka, The Modern Legal Theory Yuhikaku, p286, 2011.
[25] Kidder Robert and Miyazawa Setsuo, ‘Long-term Strategies in Japanese Environmental Litigation’, Law & Society Inquiry 18. No.4: 605–627, 1993.