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Even as the Trump administration moves to block state and local climate liability efforts, states and municipalities continue to advance lawsuits seeking to hold fossil fuel companies liable for harms associated with climate change. Most recently, the State of Hawaii initiated a climate deception lawsuit, and the City of Charleston, South Carolina, submitted a briefing in a pending case—each alleging that the fossil fuel industry engaged in a decades-long campaign to mislead the public about the risks of fossil fuel consumption and climate change. Both developments come as the Trump administration escalates its opposition to such suits, issuing on April 8 an executive order (EO), Protecting American Energy From State Overreach, targeting and filing lawsuits making constitutional challenges to state-led climate litigation and legislative actions—including a preemptive action against Hawaii just days before the state’s filing.
Hawaii Files Suit Against Oil Companies—Despite DOJ’s Preemptive Legal Threat
On May 1, 2025, Hawaii Attorney General, Anne Lopez, filed suit in Hawaii state court against 20 major oil companies and the American Petroleum Institute. The state alleges that the defendants were aware, as early as the 1960s, that fossil fuel combustion posed “catastrophic” climate risks but concealed those risks from the public and actively misled consumers through a decades-long “greenwashing” campaign by marketing their products as safe, necessary or environmentally friendly.
The complaint cites an array of climate-related harms facing the state—including coastal erosion, sea level rise, the devastating Maui wildfires of 2023, coral reef degradation, and threats to Native Hawaiian cultural practices—as consequences of the defendants’ conduct. The state also argues that the companies’ alleged failure to warn and affirmative misrepresentations delayed the transition to a lower-carbon economy.
Hawaii asserts eight causes of action under state law, including negligence, public and private nuisance, trespass, failure to warn, and violations of Hawaii’s Unfair or Deceptive Acts or Practices (UDAP) statute. The complaint seeks compensatory and punitive damages, natural resource damages, and civil penalties and treble damages under the UDAP statute, as well as equitable relief to fund climate adaptation, mitigation and resilience efforts.
Notably, the state’s lawsuit was filed the day after the U.S. Department of Justice (DOJ) filed lawsuits against Hawaii and Michigan, seeking to preemptively enjoin the states from pursuing precisely this kind of tort-based climate litigation. In those complaints, the DOJ argues that such state actions are preempted by the Clean Air Act and violate the Constitution’s structural limitations on state authority, including the Dormant Commerce Clause, Foreign Commerce Clause, and the federal government’s exclusive authority over foreign affairs and national energy policy. The DOJ’s complaints rely heavily on President Trump’s April 8 EO, which directs the Attorney General to challenge state and local efforts deemed to burden domestic energy production—including, expressly, climate change litigation.
Against this backdrop, Hawaii’s lawsuit emerges as a test case in the growing legal battle over whether states can pursue tort claims for climate-related damages and whether the federal government can lawfully block them.
Charleston Rejects Executive Order’s Relevance in Ongoing Litigation
On April 17, in the City of Charleston’s pending climate deception lawsuit against more than two dozen fossil fuel companies, a South Carolina state court requested briefing on whether the April 8 EO has any implications on the litigation. Like Hawaii’s newly filed case, Charleston’s 2020 complaint alleges that the defendants misled the public about the climate risks associated with fossil fuel use, resulting in harms including sea level rise, tidal flooding and infrastructure damage.
In a joint response submitted on May 5, the City of Charleston argued that the EO has no bearing on the case. Citing the Order’s stated purpose—to challenge state and local actions that “burden[] the identification, development, siting, production, or use of domestic energy resources”—and its prospective nature, the City maintained that its lawsuit imposes no such burdens. Rather, the case targets past deceptive conduct. “[T]he focus of this lawsuit,” the City wrote, “is Defendants’ deceptive conduct that has caused the City’s climate change injuries.”
Charleston further argued that the EO should not be given any deference:
The City submits that any deference to this Executive Order, especially given its forward-looking intent, threatens the core import of judicial review. Neither this Executive Order nor the Executive branch possess constitutional authority to dictate to this Court or the judicial system how to rule in pending cases.
The defendants, by contrast, argued that the EO reinforces their position that the claims must be dismissed as preempted by the Clean Air Act and barred by the U.S. Constitution. The defendants also pointed to the DOJ’s recently filed lawsuits against Hawaii and Michigan to block similar climate tort actions as further evidence of the federal government’s opposition to non-federal efforts to impose liability for global emissions. The defendants concluded by requesting a hearing on their pending motions to dismiss.
Climate Attribution Science Continues to Develop
As climate liability lawsuits advance, advocates hope that ongoing developments in the evolving field of climate attribution science will help address one of the most challenging, and yet-untested legal hurdles to recovery: causation. In a recent example, a paper published in the scientific journal Nature last month outlines a peer-reviewed “end-to-end” attribution framework that aims to connect emissions from individual fossil fuel producers to quantifiable, localized climate-related damages. The paper estimates that emissions traceable to major oil and gas companies have caused trillions of dollars in global heat-related economic losses between 1991 and 2020. The authors argue that their methodology supports the legal standard for “but for” causation and could be used to assess liability for both cumulative and event-specific climate harms, such as heatwaves and extreme weather events.
Plaintiffs in cases like those filed by Hawaii and Charleston may seek to utilize this paper and others in a rapidly growing body of attribution science to support proof of causation. However, because no U.S. court has yet reached the expert opinions admissibility stage—let alone a liability determination—in these climate tort cases, it remains to be seen whether judges will find such emerging methodologies sufficiently reliable to satisfy the standards for admissibility of expert evidence. And, even if so, it remains to be seen whether and to what extent courts will find them sufficient to establish causation under applicable state tort doctrines against the weight of any rebuttal evidence that may be developed.
Looking Ahead: Courts Will Decide the Balance of Power
These legal battles are unfolding in courts across the country, with several constitutional questions now squarely at issue. Chief among them are the limits of state authority to regulate or seek redress for the impacts of global climate change, and the extent to which executive orders and other federal executive actions can or should influence judicial outcomes in pending state-law cases.
If plaintiffs succeed in overcoming these threshold challenges, one of their critical hurdles ahead will be proving causation. As these cases move into expert discovery and liability phases, the reliability and admissibility of emerging climate attribution science will likely take center stage—raising novel questions under Rule 702 and analogous state-law evidentiary standards.
Pillsbury will continue to monitor these developments closely and stands ready to assist clients in navigating the expanding legal, regulatory, and reputational risks posed by the evolving climate litigation landscape.
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