東京都「CO_2総量削減義務・排出量取引制度」に見る政策波及の可能性 : 自治体政策過程における合意形成作用を手掛かりに

In June 2008, the Tokyo metropolitan government (TMG) has established a cap-and-trade measure via its ordinance amendment. It was the first governmental attempt in Japan that engendered pro and con arguments. Yet, both sides shared the same view that the TMG's cap-and-trade can be mimicked by other local and national governments and eventually become institutionalized as a nation-wade regulatory scheme. Thus, from the perspectives of political science, this article explores the possibilities of such policy diffusion by finding factors that affected the TMG scheme's implementabilities. As a result, the article highlights the importance of the following points. 1) The composition of emission sources in Tokyo provided opportunities for political deal-makings. 2) CO₂ reduction measures were placed as a pivotal part of the campaign in hosting the 2016 Olympics. 3) Abundant expenditures and budgets were thus made possible. Because these are unique geopolitical factors that equally define Tokyo's own policy context, mimicking the TMG's cap-and-trade in areas other than Tokyo rather deprives opportunities to reach needed consensus and undermines the policy rationale for proper CO₂ reduction measures. Therefore, the article concludes that the possibilities of diffusion of the TMG's cap-and-trade occurring among the other governments are very low.