Having to face the challenges of climate change, States have committed to international obligations and have adopted measures at the European or domestic level to route to a carbon neutral society. But most obligations (at the international, European or domestic level) are short and/or non-binding; and most States still under-perform their mitigation efforts. Courts cannot replace governments and parliaments to improve a State’s climatic action, since the diktats of the rule of law and the separation of powers oppose to that. But they can control the activity of the executive and legislative branches: pressuring for regulation in cases of lack or incomplete regulatory framework; helping to unveil obligations and fill regulatory gaps; and pointing to possible regulatory pathways. Courts need to be aware of their societal function, and of their restricted, but pivotal, role in a legal system; by assuming these functions as required by the rule of law, courts can also be agents of change.