Suncor Energy (U.S.A.) Inc., Suncor Energy Sales Inc., and Exxon Mobil Corporation filed a petition for writ of certiorari asking the U.S. Supreme Court to review the Colorado Supreme Court’s May 2025 opinion holding that federal law did not preempt state law claims brought by the City of Boulder and the County Commissioners of Boulder County seeking to hold the companies liable for climate change-related injuries. The petition presented the question of “[w]hether federal law precludes state-law claims seeking relief for injuries allegedly caused by the effects of interstate and international greenhouse-gas emissions on the global climate.” The companies argued that the Colorado Supreme Court decision had deepened a “clear conflict” on the question, citing the Second Circuit Court of Appeals 2021 decision in City of New York v. Chevron Corp. and decisions by the Seventh and Fourth Circuits in cases concerning interstate pollution. The companies also argued that the Colorado Supreme Court’s decision was contrary to the views of the United States, as expressed in an amicus brief filed in the Maryland Supreme Court in July 2025 in Baltimore’s, Annapolis’s, and Anne Arundel County’s appeals of the dismissals of their climate lawsuits. In addition, the companies argued that Supreme Court review was warranted because of the “enormous legal and practical importance” of the case; they contended that the Colorado Supreme Court’s decision “perpetuates an unsustainable and chaotic patchwork of regulation of interstate and international emissions” and thereby “threatens one of this Nation’s most critical industries.”

Action by Colorado local governments seeking damages and other relief from fossil fuel companies for climate change harms.

Suncor Energy (U.S.A.) Inc. v. County Commissioners of Boulder County

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Fossil Fuel Companies Asked U.S. Supreme Court to Review Colorado Supreme Court Decision Allowing Boulder State-Law Climate Claims to Proceed

Filed

United States of America

Colorado

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An aim to achieve a quantifiable outcome within a given time-frame, set by an institution such as a national government.

Policy instruments are techniques or tools used by governing authorities to promote certain policies in order to achieve predetermined goals. Put simply, instruments are how a government tries to achieve its goals, with this taxonomy being focused on national policy instruments.

Risk is the potential for adverse consequences resulting from the dynamic interplay between (climate-related) hazards, exposure, and vulnerability of affected human or ecological systems.

Groups  of people who are adversely affected by climate change or the response to it

A set of principles, processes, and practices that build economic and political power to shift from an extractive economy to a regenerative economy.

Justice is the ethical and political framework that addresses fairness, including issues of responsibility, rights, and structural inequity.

Renewable energy means all forms of energy produced from renewable sources in a sustainable manner.

Fossil fuel is a generic term for non-renewable energy sources such as coal, fossil gas, and oil (including crude oil, and petroleum products), that can be used for electricity and heat generation. Fossil fuels are hydrocarbons formed from pressurised and heated organic material buried over millions of years.

Molecules in the atmosphere that play a key role in the greenhouse effect by trapping heat radiating from Earth’s surface.

Area of the economy in which actors engage in identical or related activities.

In human systems, the process of adjustment to actual or expected climate change and its effects, in order to moderate harm, increase resilience or exploit beneficial opportunities. In natural systems, the process of adjustment to actual climate change and its effects; human intervention may facilitate adjustment to expected climate change and its effects.

The management and allocation of funds, assets and investments to meet various objectives

Financial support to help individuals manage the effects of unexpected events, securing their livelihoods and increasing the resilience of people and businesses to the changing climate. It’s especially vital in developing regions where everyday risks, climate-related weather extremes, or crop failures can push people into poverty. Without insurance, people may have to resort to selling assets or cutting consumption to cope with losses.

Codes and standards are regulatory instruments that specify minimum standards to protect health and safety. This ranges from performance standards, which prescribe outcomes while allowing flexibility to achieve compliance, to the more prescriptive approach of technology-specific standards.

Zoning and spatial planning are both methods for guiding the distribution of people and activities in a space, and are regulatory restriction.

A ban is a legal action that prevents the sale or supply of a product or service, or that recalls a product from the market. Examples are bans on SF6, greenwashing, fossil fuel advertisement or single-use plastics.

Either money or something of monetary value is transferred between two or more organisations, people or countries.

Actions or measures to adapt freshwater systems to climate change.

Actions to adapt human health, healthcare systems and well-being to climate change.

Actions or measures to adapt freshwater, coastal and marine systems to climate change.

Hot temperature extremes are daily maximum temperatures  that were exceeded on average once in a decade or once in 50 years, and includes heatwaves.

The release of heat-trapping gases, primarily from human activities such as burning fossil fuels, agriculture and industry.

A long-lived, colourless gas, chiefly emitted from fossil fuel combustion, deforestation and cement production.

Extreme weather refers to events where a weather variable exceeds (or falls below) a threshold. Meaning it is significantly different from the average or usual weather pattern.

A drought is an extended period of unusually dry weather marked by a significant and sustained lack of precipitation, falling below a specific threshold over a large area for more than a month

Terrestrial means "of the earth" and relates to the risks to ecological system that includes all living organisms and their interactions within land-based environments, such as forests, grasslands, and deserts.

Air pollution involves harmful contaminants in the air, affecting both indoor and outdoor environments. It can lead to health issues like respiratory diseases and heart problems, and climate impacts such as global warming. Pollutants can damage plants, trees, habitats, and water bodies like rivers and lakes.

Oil is a combustible liquid fossil fuel composed mainly of hydrocarbons, occurring as crude oil and refined into petroleum products such as petrol, diesel and kerosene.

Fossil gas, commonly known as natural gas, is a fossil fuel consisting chiefly of methane with smaller amounts of other hydrocarbons and trace gases, found in underground deposits.

Coal is a combustible sedimentary rock formed from carbonised plant matter, rich in carbon and hydrocarbons, and occurring in several main types including hard coal and brown coal.

People with different national or cultural traditions from the dominant population

Social and cultural groups that share collective ancestral ties to the lands and natural resources where they live, occupy or from which they have been displaced

Work that is productive and delivers a fair income, security in the workplace and social protection for all, better prospects for personal development and social integration, freedom for people to express their concerns, organize and participate in the decisions that affect their lives and equality of opportunity.

Any compulsory, unrequited payment to the government levied on corporations or individuals. This can be for environmental reasons, such as introducing a Carbon tax to set a price that emitters must pay for the greenhouse gases they emit.

Activities of industries that extract natural resources, such as mining, oil, and gas, for commercial use.

The activities of industries involved in the production, distribution, and sale of energy, including electricity, gas, and renewables.

Activities that involve planning, designing and building infrastructure, residential, and commercial structures.

This sector involves the wholesale and retail selling of goods.

This sector involves activities to move goods and people, alongside the storage of products.

This sector creates and distributes information and entertainment through television, radio, print, and digital platforms.

Activities of government agencies and institutions that provide public services, enforce laws and manage public resources.

This sector includes firms and individuals offering specialised expertise in fields such as law, accounting, consulting, science and engineering.

This sector involves the distribution, treatment, and conservation of water resources.

Climate change can have a range of impacts on technological system. Extreme weather events can cause infrastructure failures like power outages or damage to roads and bridges, as well as the impacts from waste following natural disasters. Human activities also cause technological impacts, such as the risks posed by oil spillage and leaks.

Any substance with chemical properties that can cause physical harm to people or damage the environment, including ammonia, carbon monoxide, phosphine, chlorine, arsenic, cadmium, mercury, pesticides, dioxins, microplastics, benzene, asbestos, aflatoxins, fluoride, methanol, and toxins from marine sources.

Slow onset events evolve gradually from incremental changes over many years or from increased frequency or intensity of recurring events. As defined in the Cancun Adaptation Framework (2010), slow onset events include risks and impacts from rising temperatures, desertification, biodiversity loss, land and forest degradation, glacial retreat, ocean acidification, sea level rise, and salinization.

Heavy precipitation refers to any form of weather where substances fall from the sky, including rain, snow, sleet, or hail.

The cryosphere is the frozen part of the Earth—it includes sea ice, glaciers, snow, and ice sheets. It helps regulate the climate and weather by reflecting sunlight. Rising temperatures are causing melting, leading to sea ice loss, glacier collapse, and glacier landslides and avalanches. This threatens the livelihoods of around 700 million people who rely on the cryosphere for food, water security, and cultural practices.

Fossil Fuel Companies Asked U.S. Supreme Court to Review Colorado Supreme Court Decision Allowing Boulder State-Law Climate Claims to Proceed

Policy instrument

Risk

Impacted group

Just transition

Renewable energy

Fossil fuel

Greenhouse gas

Economic sector

Adaptation/resilience

Finance