The Suncor Energy case reached the Supreme Court for argument on Oct. 5, First Monday, spotlighting a dispute over whether federal law precludes Colorado state-law claims seeking billions in climate-related damages tied to interstate and international greenhouse-gas emissions. The hearing also followed the late recusal of Justice Samuel A. Alito Jr. a week before argument.
Suncor Energy case and preemption
The central question is whether federal law forecloses state tort claims over costs allegedly stemming from global climate change attributed to fossil fuel producers. The analysis turns on constitutional structure and Supreme Court precedent, according to the parties and several justices’ lines of questioning.
Article VI’s Supremacy Clause makes the Constitution, federal statutes, and treaties the supreme law of the land. Beyond familiar doctrines like express, conflict, obstacle, and field preemption, the Court has recognized structural and foreign-affairs preemption that do not depend on a specific conflicting statute.
In 1968, the Court in Zschernig v. Miller invalidated an Oregon inheritance law for intruding on foreign affairs absent a conflicting federal enactment. In 2003, American Insurance Association v. Garamendi held that a California disclosure law conflicted with presidential foreign policy expressed through executive agreements that contained no explicit preemption clauses.
Interstate emissions disputes have long been treated as matters of federal concern. In 1907, Georgia v. Tennessee Copper Co. explained that states, by entering the union, surrendered unilateral remedies for out-of-state nuisances and instead must proceed in the Supreme Court’s original jurisdiction.
In 2011, American Electric Power Co. v. Connecticut reaffirmed that borrowing any single state’s law for interstate air and water controversies is inappropriate and emphasized that crafting policy in this domain is for Congress, not the courts.
The Boulder litigation in the Suncor Energy case
Boulder County and the City of Boulder sued Suncor and Exxon Mobil in Colorado state court, seeking monetary relief under state-law theories including public nuisance and consumer deception. The filings allege that the companies’ global production, refining, promotion, marketing, and sale of fossil fuels contributed to worldwide emissions, worsening climate impacts such as wildfires, drought, and flooding in Boulder.
The Colorado Supreme Court rejected the companies’ preemption defenses, concluding that federal law does not bar Boulder’s claims. It reasoned that the plaintiffs are not seeking to abate emissions but to recover damages for producing and marketing fuel, which the court characterized as a traditional state responsibility rather than an attempt to regulate emissions directly.
Other courts have disagreed. In 2021, the U.S. Court of Appeals for the 2nd Circuit in City of New York v. Chevron Corp. dismissed similar claims, holding that artful pleading could not disguise a suit over global greenhouse-gas emissions and that such litigation lies beyond the limits of state law.
Roughly 60 states and localities have filed comparable suits, and more could follow if Boulder prevails. At argument, Chief Justice John G. Roberts Jr. observed that a ruling for Boulder might prompt municipalities nationwide to file similar actions.
Where constitutional limits apply
The energy companies contend that the Constitution’s structure prevents one state from using its law to govern claims involving interstate and international emissions. They argue that state sovereignty carries territorial limits and that foreign emissions implicate the federal government’s exclusive foreign affairs power.
Boulder counters that the 10th Amendment reserves to the states all powers not delegated to the federal government or prohibited by the Constitution, and therefore state law may operate absent an explicit constitutional bar or conflicting federal statute.
The 10th Amendment, however, does not delineate the inherent limits on state sovereignty that predate and were preserved by the Constitution. Georgia v. Tennessee Copper explained that states relinquished certain unilateral remedies upon joining the union, receiving federal forums applying federal law instead.
In 1907, Kansas v. Colorado described “equality of right” as the cardinal rule among states, under which each stands on equal footing and cannot impose its legislation on another. Boulder’s claims seek billions for alleged harms linked to worldwide activities, and a judgment could affect company conduct well beyond Colorado’s borders regardless of other states’ policies.
The argument is even more direct for international emissions. Quoting Justice Joseph Story, the Court stated in 1995’s U.S. Term Limits, Inc. v. Thornton that a state cannot reserve what it never possessed.
In 2007’s Massachusetts v. EPA, the Court noted that a state cannot negotiate an emissions treaty with foreign nations because those sovereign prerogatives rest with the federal government. Assigning responsibility between foreign and domestic emitters through a jury verdict would implicate those exclusive federal powers.
Several justices signaled that Boulder’s tort claims ultimately hinge on emissions. Chief Justice Roberts described the suit as an effort to reduce emissions, and Justice Elena Kagan said the theory depends on the defendants’ responsibility for excessive emissions.
The Colorado Supreme Court viewed the claims differently, concluding that damages do not regulate emissions because no abatement order is requested. Supreme Court opens term with Suncor Energy v. Boulder County provided additional context on how the justices framed the stakes in the case.
Supreme Court precedent recognizes that damages can operate as regulation. In 2012’s Kurns v. Railroad Friction Products Corp., the Court said regulation can be effectively exerted through damages awards.
In 1987’s International Paper Co. v. Ouellette, the Court barred suits against out-of-state pollution sources under the affected state’s law to prevent states from doing indirectly what they cannot do directly. During argument, Justice Amy Coney Barrett questioned why Colorado tort law should achieve what the Constitution would forbid Colorado from mandating through an emissions cap in other states.
Boulder argues that states may apply their law to out-of-state conduct causing in-state injury, a principle suited to direct and traceable effects like a gunshot across a border or lending a car for use in a neighboring state, not widespread atmospheric emissions.
As American Electric Power observed, emissions from one state may contribute no more to flooding elsewhere than emissions from another country. In 1909’s Nielsen v. Oregon, the Court held that a state cannot penalize conduct performed in another state when that other state has authorized it.
Today, several states, including Iowa, Oklahoma, Tennessee, Utah, and Texas, have enacted limits on climate-change liability, while West Virginia has adopted a policy to promote oil and gas development. Twenty-six states filed a brief backing the companies, while Colorado and 18 states supported Boulder.
The split underscores why one state’s law cannot govern the nation or its sister states’ policies. Resolving Boulder’s claims would require apportioning responsibility between domestic and international emissions, raising foreign-affairs preemption concerns.
Under Garamendi, courts weigh a state’s traditional interests against potential conflict with federal foreign policy. Boulder’s claims face difficulty on both fronts because states have not traditionally regulated how fuels are produced and sold overseas, and emissions are a frequent subject of international diplomacy.
Allowing a Colorado jury to assign shares of responsibility among global producers would intrude on the federal government’s foreign relations role. Nothing in Garamendi requires a binding treaty before state law must yield; the absence of such an agreement may reflect ongoing negotiations or executive judgments about national interests.
Conclusion
Climate disputes are inherently interstate and international. Emissions cross borders, and Colorado’s claims reach conduct and policies far beyond the state and even the country.
Through Suncor, the Court could reaffirm equal state sovereignty by holding that the Colorado suit is preempted on constitutional grounds, offering guidance to lower courts managing a growing number of state-law cases aimed at interstate and international phenomena.