Does the political ideology of negotiating parties influence the design of international environmental agreements? This article distinguishes between leftist and rightist executives in democracies to develop a twofold argument. First, left-leaning democratic governments tend to be generally more environmental-friendly, which implies that they should favor designs that are more conducive to effective institutions. Second, leftist democratic executives are commonly less concerned about sovereignty costs. Both mechanisms suggest that environmental treaties likely comprise “legalized,” i.e., hard-law elements when left-wing democracies negotiate their design. The empirical implication of the theory is tested with quantitative data on international environmental agreements since 1975. The findings report an association between leftist ideology in democracies and agreement legalization, although this is driven by aspects of sovereignty delegation. This article contributes to the literatures on environmental institutions, international cooperation more generally, as well as party politics.

谈判各方的政治意识形态是否影响国际环境协定的设计？本文区分了民主国家的左派和右派高管，以展开双重论证。首先，左倾民主政府通常更环保，这意味着他们应该支持更有利于有效制度的设计。其次，左翼民主高管通常不太关心主权成本。这两种机制都表明，环境条约可能包含“合法化”，即当左翼民主国家协商其设计时，硬法元素。该理论的经验意义通过 1975 年以来国际环境协定的定量数据进行了检验。调查结果报告了民主国家中的左翼意识形态与协议合法化之间的关联，尽管这是由主权授权方面驱动的。本文对有关环境机构、更广泛的国际合作以及政党政治的文献有所贡献。