The precautionary principle has been implemented in many fields including environment protection, biological diversity, and climate change. In the field of international nuclear safety regulation, the implementation of this principle is in an ongoing process. Since Japan declared to discharge Fukushima nuclear waste water into the ocean, the precautionary principle was put on the stage, and some debates are invoked on it. As is observed by this article, the precautionary principle has not been effectively implemented in nuclear safety regulation, specifically in nuclear safety law making, law enforcement, and judicial application. The reasons can be found from two main challenges: indeterminacy of perceived risk level required to justify precautionary action and hard balance of national interest and community interest in nuclear safety. In a long-term perspective, the framework of international nuclear safety regulation has to respond to these challenges, both by clarifying the precautionary principle in legal binding nuclear safety documents and moving towards a more transparent, fair, and effective enforcement regime in order to promote safer, more sustainable, and efficient civilian nuclear utilization around the world.

With Antarctic tourism gaining increasing popularity in the twenty-first century, decarbonization in Antarctic tourism shows a growing importance. The challenge of decarbonizing Antarctic tourism lies in governing emissions generated primarily in global aviation and shipping sectors, while relying on the Antarctic Treaty System (ATS) for regional environmental governance. This article focuses on this regulatory divide by comparing two governance layers: the global sectoral regimes for aviation and shipping, and the ATS as the regional regime. By conducting a doctrinal analysis and qualitative assessment, it examines the scope of legal obligations and implementation of both governance layers. It identifies hurdles behind the overlaps of regulations by the International Maritime Organization (IMO) and self-regulation by International Association of Antarctica Tour Operators (IAATO), and critical gaps within the ATS itself. It also argues that the global sectoral regimes display an applicability gap in governing Antarctic tourism and the ATS exhibits a jurisdictional gap. Therefore, effective governance on decarbonization of Antarctic tourism requires an integrated governance that explicitly tackles with the hurdles and bridges the gaps, fostering institutional interaction between the sectoral and Antarctic regimes and institutional development within the ATS. This underscores the urgent need for policymakers to develop coordinated strategies that align Antarctic environmental governance with global transport decarbonization ambitions.