The United States faces a potential turning point in the relationship between state and federal regulation of environmental issues. With the election of President Barack Obama, who has signaled a commitment to taking action in the area of carbon emissions regulation, the national government may step into an arena where the states are already playing, setting up a federalism debate to determine the better actor to enact meaningful and efficient environmental protection. Effectiveness in this area depends on the balance between quick enactment to prevent increased emissions (and further harm) and the comprehensiveness required to address this national and global issue. This Comment examines the Regional Greenhouse Gas Initiative to illustrate how the use of a seldom-examined constitutional tool--consent under the Compact Clause--could enable states to form efficient and effective regional regulatory schemes that could be meaningful units within the greater system of federalism.