Judge Lets First-Ever Wrongful Death Climate Case Against Big Oil Head Toward Trial

SEATTLE — A King County judge has rejected a bid by seven of the world's largest oil and gas companies to throw out what is believed to be the first wrongful death lawsuit to blame a single individual's death on climate change, clearing the way for the case to move into discovery.

Superior Court Judge Matthew Lapin ruled July 8 that the lawsuit, brought by Misti Leon over her mother's 2021 heat-related death, is not preempted by federal law, rejecting the defendants' argument that the case amounted to an improper attempt to regulate greenhouse gas emissions through the courts. Lapin wrote that the case is narrower than that, seeking damages for one woman's death rather than broader climate remedies.

Leon sued ExxonMobil, BP, Chevron, Shell, ConocoPhillips, Phillips 66 and Olympic Pipeline in King County Superior Court in May 2025, alleging the companies knew for decades that burning fossil fuels was heating the planet but ran a coordinated campaign to sow public doubt about that science rather than warn consumers.

According to the complaint, Leon's mother, 65-year-old Julie Leon, was driving through Seattle on June 28, 2021 — the third consecutive day of triple-digit heat during the Pacific Northwest's record-breaking "heat dome" — when her car's broken air conditioning left her overcome by heat. She managed to pull over before losing consciousness; a bystander found her unresponsive about two hours later. Paramedics performed extensive CPR but could not revive her; her official cause of death was hyperthermia, with an internal body temperature of 110 degrees.

The lawsuit seeks damages under Washington's wrongful death and product liability statutes, arguing the companies failed to warn the public of foreseeable dangers from their products and that their alleged disinformation campaign delayed a shift to cleaner energy that could have protected people like Julie Leon.

Timothy Bechtold, an attorney representing Leon's estate, said the family was glad the court wasn't swayed by the defendants' array of arguments against letting the case proceed.

The ruling is the latest in a wave of climate-related lawsuits brought by individuals, cities and states against fossil fuel companies under state consumer protection and tort theories rather than federal environmental law, a strategy several state supreme courts have similarly allowed to proceed toward trial.

The case is Leon, et al. v. Exxon Mobil Corp., et al., King County Superior Court case number 25-2-15986-8 SEA. Case docket: https://trellis.law/case/53033/25-2-15986-8-sea/leon-et-ano-vs-exxon-mobil-corp-et-al