Several free trade agreements extend their dispute settlement mechanisms to environmental obligations that ‘affect trade or investment’ between contracting parties. The recently concluded Comprehensive and Progressive Agreement for Trans-Pacific Partnership (‘CPTPP’) takes such attempt to the next level by extending its dispute settlement mechanism even to a measure that does not necessarily affect trade or investment between the contracting parties. Unfortunately, however, the conventional trade dispute settlement mechanisms are not designed to enforce obligations that are ‘purely environmental’ in nature, and as such, do not lend effective mechanisms to enforce such obligations. After briefly introducing the evolution of the trade-environment convergence in international law, this article observes systemic limitations of the conventional trade dispute settlement mechanisms in enforcing purely environmental obligations through an analysis of the CPTPP’s rules on fisheries subsidies. Thereafter, this article proposes certain modifications to the conventional trade dispute settlement mechanisms for effective enforcement of purely environmental obligations.