Juliana Leon Died in a Climate-Linked Heat Wave. Her Daughter Is Suing Big Oil.

Can a lawsuit hold fossil fuel companies responsible for climate-change and its impact? That’s the question a Washington State-based woman is hoping to answer. Misti Leon is suing several big oil companies — including ExxonMobil, Chevron, BP, and others — over the 2021 heat-related death of her mother Juliana, who died during a record-breaking heat dome over the Pacific Northwest.

For years, individuals and institutions have attempted to protect human lives from climate change using litigation. In 2015, a public interest law firm called Our Children’s Trust, representing nearly two dozen young people sued the federal government for failing to protect them against the impending impacts of fossil fuel emissions. Courts dragged their feet for more than a decade only for the case to reach a dead end at the United States Supreme Court in 2025.

Leon’s civil suit is significant, not just because a Washington judge unexpectedly cleared the case for discovery and trial, but because Leon can directly link her mother’s death to climate change. Scientists concluded that the 2021 heat dome was, in the words of one research paper, “virtually impossible without human-caused climate change.” It’s about a crime that already occurred instead of hypothetical harm.

“Ms. Leon’s case is unique in that it is the first of its kind to seek to hold big oil companies accountable for their role in an individual’s death in a climate-related disaster,” Mike Meno, communications director at the Center for Climate Integrity, a nonprofit advocacy group that supports community efforts to hold Big Oil accountable for climate change, explained in an interview.

Juliana Leon was one of an estimated 1,200 people across the Pacific Northwest whose deaths were linked to the heat dome. “She was found unresponsive in her car,” said Meno. “The medical examiner determined that her death was caused by hyperthermia,” a condition that is the opposite of the more well-known cold-related condition of hypothermia.

Hyperthermia-related deaths have sharply risen over the past decade, a predictable outcome of fossil fuel emissions. Oil companies such as Exxon have long been aware of the devastating impacts their product would have on the climate. “Major oil and gas companies decades ago knew, their own scientists told them internally, that if we kept burning fossil fuels, it would lead to, in the words of one internal Exxon document, potentially catastrophic events, just like the 2021 Pacific Northwest heat dome,” said Meno.

Big Oil’s failure to act on this information has drawn comparisons to Big Tobacco. Companies like Philip Morris knew about the impacts of cigarette smoking on human health and kept it secret for years. Since that information was made public, individuals suffering from their addictive products have sued repeatedly and won.

A major lawsuit brought by state attorneys general culminated in 1998 in what became known as the Master Settlement Agreement, where dozens of tobacco companies settled to the tune of billions of dollars for public health. Notably, the federal government also sued tobacco companies for violations of racketeering laws over their deception.

Yet while individuals and states are taking action in the case of oil companies, the federal government clearly has no interest in holding Big Oil accountable for climate change. Instead, President Donald Trump says he wants the Justice Department to investigate fossil fuel companies for raising oil prices in the wake of the Iran war. This appears to be a classic case of deflection, given that a majority of voters blame Trump for price increases at the pump. He isn’t interested in holding companies accountable for climate change; he’s upset they made it harder for people to consume oil. Moreover, his administration is suing states for trying to enforce environmental regulations aimed at oil companies.

In addition to keeping their own research secret, fossil fuel companies spent years sowing doubt over the cause-and-effect relationship between greenhouse gases and a warming climate. “What that decades-long deception campaign did is it stole a generation’s worth of time when action could’ve been taken, and we could’ve averted the worst of some of these climate disasters,” said Meno.

This year, more extreme weather records are expected to be broken as climate change intensifies. The first half of 2026 was the third-warmest half-year on record. An El Niño phenomenon developing this year is expected to be one of the strongest in modern history.

Whether or not the Trump administration admits that the climate is changing, Americans know it is. “Anyone of a certain age who can look back over enough time just knows, as a matter of common sense, that the climate we are all living in today is not what we had a few years ago,” said Meno.

The industry knows it too — and, according to Meno, oil companies “are in absolute panic mode, fighting tooth and nail to escape accountability.” Leon’s lawsuit is hardly the only one they fear. Numerous states, counties, cities, and tribal governments are suing Big Oil, and making headway.

Meno explained that companies have “been pleading with the U.S. Supreme Court to take up one of these cases for years.” The Supreme Court finally agreed to review a case in Colorado where that state’s supreme court in May 2025 ruled the City of Boulder and Boulder County could move forward with discovery and trial in their suit against ExxonMobil and Suncor.

Not content with leaving it to the U.S. Supreme Court, Big Oil has been lobbying Congress to grant the industry immunity over its role in climate change — and conservative lawmakers have complied. In April, Wyoming Rep. Harriet Hageman and Texas Sen. Ted Cruz introduced the “Stop Climate Shakedowns Act of 2026.”

If Congress were to pass the bill, according to Meno, it “would be a truly unprecedented legal shield that would strip the public of their right to hold these corporations accountable for the harm they’ve caused.” Meno’s Center for Climate Integrity is urging members of the public to demand their elected representatives vote against Hageman and Cruz’s bill.

Big Oil says it deserves immunity because it shouldn’t be penalized for giving the public what it wants. In a joint statement, American Fuel & Petrochemical Manufacturers President and CEO Chet Thompson and American Petroleum Institute President and CEO Mike Sommers said: “These efforts to retroactively penalize companies for lawfully meeting consumer demand are misguided and counterproductive.”

What they didn’t say is that they have worked for years to prevent fair competition from renewables. It’s why the state of Michigan launched an antitrust lawsuit against ExxonMobil, BP, Chevron, and others because they acted “as a cartel … to forestall meaningful competition from renewable energy in order to maintain their dominance.”

Fossil fuel companies have long known their products are deadly, kept it secret, unfairly ensured their dominance, then argued that they ought not to be sued for delivering a product the public wants. Now, as climate-related deaths stack up, the industry claims it isn’t responsible. Misti Leon, whose mother might be alive today if governments and courts had reined in Big Oil, told The New York Times: “I never would have in a million years guessed that a heat dome and climate change would be what killed my mother and what took her from me. There’s no way to comprehend that and to kind of even rationalize it.”