Legal Considerations for Carbon Mitigation by Cities

December 12, 2019 - (5 min read)

The Sabin Center for Climate Change Law seeks to partner with cities to understand the legal challenges facing cities in crafting and adopting climate-friendly laws and policies.

U.S. cities, towns, villages and counties are increasingly taking the lead on climate mitigation. Dozens of U.S. cities have set greenhouse gas mitigation targets, more than 400 U.S. mayors signed onto a joint commitment to “adopt, honor and uphold the Paris Climate Agreement goals,” and more than 90 American cities have committed to a 100% renewable energy target. These ambitious goals demand that we not only reimagine our economy and energy systems but also rethink the legal mechanisms by which we authorize and regulate our transportation, buildings, energy and waste, and the countless pieces of our lives that these sectors touch.

The Sabin Center for Climate Change Law at Columbia Law School has launched the Cities Climate Law Initiative, a project aimed at helping cities achieve their climate mitigation commitments by both addressing obstacles to advancing implementation of the laws and sharing legal tools available to help reduce urban greenhouse gas emissions. While there are shared legal challenges that all cities face in enacting climate-friendly laws and policies, there are also significant differences in the types of policies cities may be able to enact – at least in the way the community would need to go about implementing those policies.

We’ve identified five major types of legal challenges that U.S. cities face when crafting and adopting climate-friendly laws and policies:

  1. Preemption by U.S. Federal Law. Federal laws like the Clean Air Act and the Energy Policy & Conservation Act can preempt some of the policies advanced abroad, like London’s “ultra-low emissions zone.” While American cities could be preempted from implementing a low emissions zone that distinguishes among vehicles based on emissions or fuel economy, there are aspects of these policies that can be implemented here in the U.S. The Cities Climate Law Initiative helps cities understand what aspects of low emissions zone policy are legally permissible in the U.S.
  2. Adapting Policies From City to City. Laws requiring new commercial and multifamily buildings to connect to renewable energy or be solar-ready (Seattle) or to be EV-ready (Los Angeles) require more creativity to implement in cities that don’t have authority to set their building codes. Options to counteract this could include increased incentives, greening the city’s own buildings, or attaching the requirement to another legal mechanism.
  3. Navigating State Authority. U.S. cities are limited by their grant of authority from the state. Therefore, cities will need to work with their state governments to implement some climate-friendly policies. For example, New York City needed to collaborate with its state government to pass congestion pricing legislation. Additionally, public service commissions are creatures of state law, and cities may need to work with these entities on matters such as renewable procurement, distributed generation and EV charging.
  4. Emerging Businesses. Aggressive pushes by micro-mobility companies to introduce their bikes and scooters have left cities scrambling to regulate various legal issues related to permitting, public rights-of-way and disability rights. Strategies for reducing greenhouse gas emissions, including from private businesses, will continue developing rapidly.
  5. Private Contracts. Private actors will need to take action for cities to be successful in achieving their greenhouse gas mitigation goals. For example, some building emissions reductions will require landlords and tenants to realign traditional commercial lease terms, which disincentivize owner investment in building energy retrofits (aka the “split incentive problem”).

Central to all of this, of course, is equity. The significant and structural legal changes that will be needed to achieve cities’ climate mitigation goals must be implemented in a way that is just, that protects vulnerable communities and that reflects the needs of all of a city’s residents. These considerations are a significant part of crafting any laws, policies or legal tools that cities can use to combat climate change.

The Cities Climate Law Initiative is seeking U.S. cities, towns, and villages to partner with on legal questions associated with climate mitigation policies. Together, the Sabin Center and each partner city will identify a legal question, issue or obstacle, or a drafting need. The Sabin Center will conduct academic research to help inform each city’s approach to developing or implementing an identified climate mitigation policy and will provide tailored insights and learning to the city. For more information, please contact Amy Turner at

fullsizeoutput_1b23About the Author: Amy Turner is a Senior Fellow for the Cities Climate Law Initiative at the Sabin Center for Climate Change Law at Columbia Law School. Her work focuses on the laws and legal tools cities use to achieve their climate mitigation commitments. Amy has practiced in the area of environmental law for more than a decade and currently serves as co-chair of the New York City Bar Association’s Committee on Environmental Law. She can be found on Twitter at @amyturner.