The US Supreme Court ruled unanimously on Friday in favour of oil giant Chevron, overturning a lower court ruling that had ordered the company to pay $745 million in fines for polluting marshlands near New Orleans (Louisiana) and failing to rehabilitate the sites after operations ended. The court accepted Chevron's argument that, because it was acting as a contractor for the US military at the time, the case fell under federal rather than state jurisdiction. The ruling is being closely watched across the United States, as it could affect the outcome of roughly 40 similar environmental lawsuits currently pending against major energy companies in several states, where potential penalties run into the billions of dollars — since federal courts have historically been less favourable to holding oil companies liable for environmental damage.