In February 2020, a group of German youth filed a legal challenge to Germany's Federal Climate Protection Act (“Bundesklimaschutzgesetz” or “KSG”), arguing that the KSG's target of reducing GHGs 55% by 2030 from 1990 levels was insufficient. The complainants alleged that the KSG therefore violated their human rights as protected by the Basic Law, Germany's constitution.
The complaint alleged that the KSG's 2030 target did not take into account Germany's and the EU's obligation under the Paris Agreement to limit global temperature rise to "well below 2 degrees Celsius." The complainants argued that in order to "do its part" to achieve the Paris Agreement targets, Germany would need to reduce GHGs by 70% from 1990 levels by 2030. Their claims principally arose out of the principle of human dignity allegedly enshrined in Article 1 of the Basic Law; Article 2 of the Basic Law, which protects the right to life and physical integrity; and Article 20a of the Basic Law, which protects the natural foundations of life in responsibility for future generations. Complainants argued that by requiring insufficient short and medium term GHG reductions and allowing for the transfer of emission allocations between Germany and other EU Member States despite the inadequacy of the overall EU emissions reduction target, the KSG allowed climate impacts that violate these human rights
The complaint asked the Federal Constitutional Court to declare that the legislature violated the Basic Law by requiring only a 55% reduction in GHGs by 2030; declare that the legislature is required to issue new reduction quotas to ensure that Germany's emissions are kept as low as possible, taking into account the principle of proportionality; and prohibit the transfer of emissions allocations in the new regulatory regime.
On April 29, 2021, the Federal Constitutional Court struck down the parts of the KSG as incompatible with fundamental rights for failing to set sufficient provisions for emissions cuts beyond 2030. The Court found that Article 20a of the Basic Law obliges the legislature to protect the climate and aim towards achieving climate neutrality. Further, the Court stated that Article 20a "is a justiciable legal norm that is intended to bind the political process in favour of ecological concerns, also with a view to the future generations that are particularly affected." Accepting arguments that the legislature must follow a carbon budget approach to limit warming to well below 2°C and, if possible, to 1.5°C, the Court found that that legislature had not proportionally distributed the budget between current and future generations, writing "one generation must not be allowed to consume large parts of the CO2 budget under a comparatively mild reduction burden if this would at the same time leave future generations with a radical reduction burden . . . and expose their lives to serious losses of freedom.” The Court ordered the legislature to set clear provisions for reduction targets from 2031 onward by the end of 2022. According to news reports, the German government announced on April 30, 2021 that it would move quickly to adjust its climate law in response to the decision.