In the field of environmental law, be it on the domestic or the international level, it is especially difficult to develop effective regulatory systems and systems for sanctions to enforce obligations. The legal solutions employed under the auspices of the United Nations Framework Convention on Climate Change, as well as the Kyoto Protocol, constitute a fascinating attempt to address these problems, providing “a huge testing ground for the legal instruments of environmental policy, at the international as well as on the lower levels,” mirroring “enormous creativity in the design of regulatory approaches.” Even though the Kyoto Protocol, “if fully implemented, will not … avert or even slow climate change,” it serves as a fine example of emerging international composite administrations, where multiple actors participate in transnational institutions of a multilevel system, serving the common goal of mitigating climate change. The climate change regime's unique regard to flexibility in fulfillment is particularly prominent. This is complemented by especially stringent and complex compliance mechanisms, which have no parallel in other international forms of cooperation. A further significant characteristic of the system is the high degree of legitimacy enjoyed by its institutional organization, its procedures and procedural outcomes. Thus, the international cooperation under the framework of the Kyoto Protocol is a landmark: it achieves not only flexibility but also a high degree of legitimacy and represents a more mature example of the exercise of public authority by international institutions.