The US Supreme Court has opened its new term with a major climate case. On October 5, justices heard arguments in a bid by ExxonMobil and Suncor Energy. The companies want to block a lawsuit by officials in Boulder, Colorado. The city and county of Boulder sued the oil companies in 2018. They seek damages for climate change harms. Boulder accuses the companies of driving climate change and misleading the public about fossil fuel risks. The city wants money for infrastructure repairs, emergency management and public health costs. The Colorado Supreme Court let the lawsuit proceed. The companies appealed to the top court. The Trump administration backs Exxon and Suncor. It argues federal law precludes the state-law claims. A lawyer for the companies said state law cannot regulate global conduct. Nearly 60 state and local governments have filed similar suits. They seek billions of dollars from fossil fuel companies. A ruling for the companies could lead to many cases being dismissed. The court’s 6-3 conservative majority has moved US law rightward in recent years. The court also has cases on immigration and gun bans lined up this term.