This Chapter provides an overview of the Japanese legal system governing marine environmental conservation and Japan’s approach towards the management, conservation and sustainable use of marine living resources, including whales. Commercial whaling is part of the broader international environmental law debate: ensuring environmental protection while facilitating sustainable use of the natural resources of the sea. Discussions on promoting sustainable whaling at the global level are needed. The answer may be, against popular opinion in some countries, to allow limited but internationally monitored, whaling in specific locations, while stopping whaling altogether in other locations. Such approach could be adjusted based on independent and politically uncompromised scientific evidence. As scientific knowledge advances and whale stock management theories become more complex, scientific advice may not necessarily produce clear-cut answers. In situations of scientific uncertainty, the precautionary principle can allow rational decisions – provided the principle is not misinterpreted and transformed into a principle of inaction.