Misti Leon doesn’t check the weather or listen to the news when it’s hot outside. “This time of year is very difficult for me,” Leon says. Temperatures have touched the triple digits in many parts of the U.S. this summer, breaking longstanding heat records; and June and July were both the third warmest on record since 1850.
She avoids any mention of the term heat dome, which describes a weather phenomenon when the atmosphere traps hot air, raising temperatures. It was during a record-breaking heat dome in Washington in 2021, when temperatures climbed up to 108°F, that Misti lost her mom, Juliana Leon.
Julie, as everyone called her, was driving home from a doctor’s appointment on June 28, 2021 with the windows rolled down when the heat began to hit her. She pulled off the highway onto a residential street before losing consciousness, and was found two hours later. The official cause of Julie’s death was hyperthermia; her internal temperature was 110°F when she died.
Misti’s mother died at 65, on the hottest day ever recorded in Washington state, during a heat wave that was not natural. An international team of scientists found in 2022 that the heat experienced that day was “virtually impossible” without human-caused climate change. The heat dome, which stretched on from mid-June to early July, caused more than 250 deaths in the United States and 400 in Canada.
Now Misti is suing seven major oil companies—including Shell, Chevron, and ExxonMobil— for wrongful death, alleging that their knowledge that the use of fossil fuels was causing catastrophic harm to the environment, and failure to adequately warn the public, created the conditions that lead to her mother’s death.
“This is information that these companies had and they knew, and they had an opportunity to share and to potentially mitigate, and because of the choices that they made of not being open and honest about it, there’s been deaths, and that includes my mom,” Leon says.
A 2024 study from the Carbon Majors Database found that 80% of the world’s global fossil CO2 emissions since 2016, after the Paris climate agreement was signed, can be traced back to just 57 oil, gas, coal, and cement producers. Because of this, oil companies have faced their fair share of climate lawsuits over the years.
“Over the past decade, oil and gas companies have faced dozens of lawsuits in the U.S. filed by cities and states and counties that allege that the oil and gas industry covered up what it knew about climate change for decades and misled the public about the problem,” says Ben Franta, associate professor of climate litigation at the Oxford sustainable law program, who is not involved with the lawsuit. California, Minnesota, and Delaware are among the states that have filed cases against Big Oil around climate deception, though no case has gone to trial yet.
But the suit filed May 29 on behalf of Julie Leon is the first suit against oil companies based on an individual dying from an event that was driven by climate change. “They knew, decades ago, very accurately what our climate would be like today, and then they deliberately deceived the public, not just in Washington state, not just in the United States, but worldwide, about their knowledge of what their role in climate alteration is. And so we’re alleging that they’re responsible for that change,” says Misti’s attorney, Timothy Bechtold. “That alteration is what they’re responsible for. And that alteration is ultimately, what we allege, is the cause of death of Misti’s mom.”
“The stakes are enormous,” says Franta, who likens the case to precedent-setting lawsuits lodged against tobacco and opioid companies.
The suit, which was filed in the Superior Court of Washington for Kings County, is the first personal tort suit to be brought against big oil companies for personal loss—with Misti’s legal team seeking direct compensation for a wrongful death. The suit also claims that companies are liable for failure to warn under Washington’s product liability act, and public nuisance laws.
BP, which manages the Olympic Pipeline Company, ConocoPhillips, and Phillips 66 said they do not comment on pending litigation. Shell declined to comment. Exxon Mobil did not respond to TIME’s request for comment.
In a statement to TIME, Chevron Corporation’s counsel, Theodore J. Boutrous, Jr. of Gibson, Dunn and Crutcher LLP, wrote: “Exploiting a personal tragedy to promote politicized climate tort litigation is contrary to law, science, and common sense. The court should add this far-fetched claim to the growing list of meritless climate lawsuits that state and federal courts have already dismissed.”
Leon’s suit alleges that as early as the 1950s, the decade Julie Leon was born, oil companies were aware of how burning fossil fuels would impact the environment—but downplayed and withheld that information from the public. By the end of the 1970s, the American Petroleum Institute and major fossil fuel companies, like Exxon, had internal research programs on climate change.
“They were monitoring climate science and predicting when the world would notice climate change was happening, and predicting many of the impacts that we see today,” says Franta.
By the 1990s, companies began a media blitz that carried on into the early 2000s, publishing advertisements cloaked as editorials in major newspapers. Internal memos show Exxon’s strategy was to, “emphasize the uncertainty in scientific conclusions” about climate change.
Today, major oil companies acknowledge the climate crisis, but they have also faced accusations of greenwashing. A 2022 study published in the journal PLOS One examined the records of ExxonMobil, Chevron, Shell, and BP and found that the companies’ actions on climate change very rarely matched their pledges.
For Misti, the suit is about holding oil companies accountable for what they knew about climate change—and the impact concealing it had.
“I can’t bring my mom back. No matter what happens, that loss will forever be there. However, hopefully, with enough awareness and knowledge and accountability, we can keep this from happening to other people and for other people to have to experience this kind of loss,” she says. “Unfortunately, I was affected in a very deep way. But I’m not the only one, and that’s what keeps my focus on accountability.”