The US Supreme Court is hearing one of the biggest climate cases in years. Here is what it is about. In 2018, the city and county of Boulder, Colorado, sued ExxonMobil and Suncor Energy. They accused the companies of contributing to climate change and misleading the public about fossil-fuel risks, Reuters reported. Boulder wants money for climate-linked costs such as damaged infrastructure, emergency response and public-health harms. The companies say federal law blocks the state-law claims and want the case thrown out. The Colorado Supreme Court let the case proceed, so the firms appealed to the US Supreme Court. Why does this matter beyond Boulder? Nearly 60 state and local governments have filed similar lawsuits seeking billions of dollars from fossil-fuel companies. If the Supreme Court sides with ExxonMobil and Suncor, many of those cases could be dismissed. The Trump administration has backed the companies in the dispute. Justice Samuel Alito has recused himself from the case. The court opened its new term on the first Monday of October and typically decides major cases by the end of June. For cities trying to recover climate costs from oil firms, this ruling could set the rules for years to come.