This Article highlights the role that national judiciaries worldwide have played in developing the field of “climate law.” It focuses on some of the key lawsuits from civil and common-law jurisdictions that may influence climate law beyond their borders, including climate mitigation and adaptation cases as well as transnational climate cases. In particular, it considers the procedural tools and interpretive principles that judges have employed to decide novel legal issues presented by climate litigation. It concludes that judges are successfully adapting their traditional role of administration of justice to the challenges posed by climate change litigation, and holding their own governments accountable. While courts have thus far been unwilling to impose civil liability on private entities, emerging science may help address some of the causation and apportionment hurdles in these cases, and additional and collateral avenues for private-sector accountability may emerge.