This paper argues that a primary goal of the Durban Platform negotiations should be to develop an agreement that will maximize reductions in greenhouse gas emissions over time. It highlights that international agreements can serve a contractual, prescriptive, or facilitative function. It argues that, in the climate change context, the contractual and prescriptive models are not politically realistic at this time, so the 2015 agreement should focus on the law's catalytic and facilitative roles. It suggests that the 2015 agreement will have a hybrid quality, which seeks to balance national flexibility and international discipline. In many if not most countries, the climate change issue is driven more by national than by international politics, so the agreement needs to allow states to determine the content of their own commitments.