Decisions within the Clean Development Mechanism (CDM) of the Kyoto Protocol are made by an expert body that acts as a trustee agent of the member states. Trustee agents help overcome the credible commitment problems of their principals and promise reason-based decisions. In contrast to traditional principal-agent settings, trusteeship relations are typically triadic. Beside the preferences of the principals and the trustee, decision criteria provide an external point of reference. They reflect the principals’ long-term interest and define the trustee’s decision rationale. The triadic structure helps protect the autonomy of trustees and allows for making them accountable for their decisions. Accountability mechanisms intend to ensure that a trustee’s decisions are in line with established decision criteria. Against this backdrop, we explore the incentives created by the existing institutional arrangement for the making of CDM decisions and examine selected cases. We conclude that CDM arrangements provide a model for nonpartisan international regulation.