In April 2024, the Grand Chamber of the European Court of Human Rights (“ECtHR”) delivered its landmark judgment in Verein KlimaSeniorinnen Schweiz v. Switzerland (“KlimaSeniorinnen”). Since then, the decision has shaped discussion across climate litigation in Europe and beyond. The next major test for Strasbourg may now be Müllner v. Austria — a case that many observers predict could clarify how the Court’s climate jurisprudence applies to individual applicants alleging concrete climate-related harm (see e.g. here, and here). Müllner is significant in at least two respects:

First, it may offer the Court its first genuine opportunity to demonstrate how the principles articulated in KlimaSeniorinnen translate to the case of an individual applicant.

Second, it brings into focus another unresolved issue: whether a State may rely on compliance with EU climate law as sufficient to discharge its obligations under the European Convention on Human Rights (“ECHR”).

In that sense, Müllner is more than just a sequel to KlimaSeniorinnen. It has the potential to become a pivotal case for the Court’s developing climate jurisprudence, particularly as regards individual victim status, the scope of States’ positive obligations, and the position of EU climate law within the Convention framework.

Individual Victim Status in the Face of Climate Change

Described as the “most personal climate case in the world”, Mr Müllner’s case is remarkable for several reasons, most notably for the immediacy with which he experiences the effects of climate change and the precision with which these can be documented. Mr Müllner lives with multiple sclerosis (“MS”), an autoimmune neurodegenerative disease that, in his case, is further aggravated by Uhthoff’s Syndrome. While many persons with MS commonly exhibit heightened sensitivity to external temperature changes, Uhthoff’s Syndrome is particularly significant because rising temperatures intensify the MS symptoms patients experience on a daily basis.

In practical terms, when temperatures exceed 25 degrees Celsius, Mr Müllner can no longer move independently and must rely on an electric wheelchair. This has consequential implications for his private and family life, imposing severe and compounding constraints on his everyday activities. Those constraints are likely to intensify over time, both as Mr Müllner ages and, more importantly, as the planet warms and the annual number of hot days increases (on this point, see the very relevant study by Temple et al., Anthropogenic Climate Change Amplifies Risk of Multiple Sclerosis Symptoms in Austria). For Mr Müllner, climate change is therefore neither an abstract concern nor merely a future risk: it translates into an immediate and tangible deterioration in his physical condition as temperatures rise.

From a legal perspective, he falls squarely within the framework developed by the Court in KlimaSeniorinnen: he is “subject to a high intensity of exposure to the adverse effects of climate change”, while his heightened vulnerability to rising temperatures clearly demonstrates a “pressing need to ensure [his] individual protection” (KlimaSeniorinnen, [487]).

Mr Müllner’s case fits so closely within the KlimaSeniorinnen criteria for individual victim status, that one might wonder whether the Court deliberately sequenced the climate cases pending before it to develop its jurisprudence in the most incremental, legally coherent, and perhaps politically acceptable manner possible.Seen in that light, the procedural chronology is striking: although Mr Müllner’s application was lodged in March 2021, it was not communicated to Austria until 18 June 2024, whereas Duarte Agostinho, KlimaSeniorinnen, and Carême (filed in September 2020, November 2020, and January 2021 respectively) were communicated considerably earlier (in November 2020, March 2021, and May 2021), and all resulted in judgments delivered on 9 April 2024.

Interplay Between EU Climate Law and ECHR Protection

Müllner v. Austria is significant for more than the question of victim status. The case also raises a structurally more difficult issue: whether compliance with EU climate law is sufficient to discharge a State’s positive obligations under Article 8 ECHR. This question gives the case a systemic significance extending well beyond Austria.

Unlike Switzerland in KlimaSeniorinnen, Austria has relied extensively on its EU membership and the climate change mitigation obligations arising from EU law in building its defence. One of Austria’s main arguments rests on the presumption developed by the ECtHR in the Bosphorus Hava Yolları Turizm ve Ticaret Anonim Şirketi v. Ireland case (the “Bosphorus doctrine”). The Bosphorus doctrine establishes a rebuttable presumption of ECHR compliance for states executing legal obligations flowing from international organisations (such as the EU) provided that the organisation offers a level of fundamental rights protection “equivalent” to that of the Convention.

Austria contends that, as an EU member state, the measures it has adopted — including its climate mitigation targets under the EU Effort Sharing Regulation (“ESR”) — comply with EU legislation addressing climate change mitigation. On that basis, Austria argues that these measures should be presumed to be compliant with the positive obligations it owes Mr Müllner under Article 8 ECHR.

Mr Müllner, however, responds that unlike the obligations arising under the Convention, EU climate law is not concerned with the protection of individuals’ fundamental rights and that more ambitious measures are required if Austria is to satisfy the positive obligations under Article 8 ECHR. These obligations include ensuring compliance with the 1.5°C target of the Paris Agreement, quantifying a corresponding fair share carbon-budget, and implementing the required measures.

Quoting the EU Commission’s own submission, Mr Müllner recalls that EU climate law only sets minimum climate targets (Article 1, ESR). As the Commission itself acknowledges, “nothing precludes Member States from adopting even more ambitious GHG emissions reduction targets at national level.” Relying on the findings contained in the 2023 Report of the EU’s own climate advisory body, the European Scientific Advisory Board on Climate Change (“ESABCC” and “ESABCC Report”), Mr Müllner demonstrates that the EU’s current emission reduction targets permit substantially higher emissions than “even an ‘equal per capita emissions’ quantification approach would entitle it to use”, and therefore fall short of the obligations identified by the Court in KlimaSeniorinnen.

In its report, the ESABCC concluded that the EU’s remaining 1.5°C-aligned carbon budget was, at most, 27 gigatonnes of CO₂ from 2020, using an “equal per capita” approach (for pieces explaining the role of the ESABCC Report and these figures, see respectively here and here). At the level of individual member States, those findings suggest that existing EU climate law targets do not reflect a fair allocation of the mitigation burden that each State ought to bear.

If upheld, Mr Müllner’s arguments could lead to a finding that Austria is violating Article 8, due to its failure to have in place a framework compatible with these obligations. In essence, Müllner v. Austria will most likely require the Court to consider whether the EU climate law framework, and its Member State-specific mitigation targets, satisfy the positive obligations required under the ECHR. Accepting Mr Müllner’s arguments on this point would not only concern Austria’s domestic climate framework; it would also raise the broader question whether the level of protection offered by EU climate law is, in Convention terms, sufficient where fundamental rights are at stake.

In that sense, Müllner has the potential to reopen — in a new context — the longstanding and delicate debate about the relationship between EU law and the Convention system (a subject which exceeds the remit of this piece, but that is widely covered, see for instance here, here, and here).

An Opportunity to Carry Forward the KlimaSeniorinnen Momentum

Mr Müllner filed his last submission in March 2025 and is still awaiting a decision. The fact that the case remains pending despite having been granted priority status has inevitably prompted questions about the broader climate in which the Court is currently operating.

Since KlimaSeniorinnen, climate adjudication has become more politically contested (see e.g. critical reactions in Switzerland, commented on here, here, here, and here, but also elsewhere e.g. here), while climate ambition has weakened in many parts of Europe and beyond (on this topic see here). Whether or not these developments have affected the pace of the proceedings, they form an important backdrop to the Court’s next move in this area.

Climate change is undoubtedly one of the most frightening, pressing and complex challenges confronting present and future generations alike. Jurisprudential breakthroughs such as the KlimaSeniorinnen judgment demonstrate that judicial intervention can help catalyse meaningful legal and political change. They also show that principled adjudication remains capable of advancing protection, enhancing accountability, and triggering real action in the face of an escalating climate crisis.

The questions raised in Müllner v. Austria are unlikely to yield easy answers. Yet they are questions the Court cannot avoid if it is to remain faithful to its role as a guarantor of fundamental rights within the Council of Europe. Much therefore depends on whether the Court is prepared to carry forward the momentum created by KlimaSeniorinnen and to address, with the same clarity and resolve, the complex issues now before it.

At stake is not only the outcome of one important case, but also the credibility of the Court’s emerging climate jurisprudence at a moment when legal ambition is increasingly tested by political and institutional hesitation.