The California Supreme Court has struck down a county's voter-approved ban on oil and gas drilling, ruling that state law largely reserves those decisions to regulators.

Handing a win to Chevron and other fossil fuel companies, the seven-member court on Thursday unanimously held that Monterey County’s ban conflicts with a state law that gives California regulators oversight over what “methods and practices” can be used to extract fossil fuels.

Because the county’s initiative – which prohibits new oil well drilling and the use of certain extraction methods – essentially makes those decisions “in lieu of” state regulators, it cannot stand, wrote Justice Martin Jenkins for the court.

Hollin Kretzmann, an attorney who defended the ballot initiative on behalf of the local advocacy group Protect Monterey County, said in a statement that county residents “now need to wait even longer for protections” that they already voted to enact.

Theodore Boutrous, an attorney who represented Chevron, said the company is pleased with the decision, which upholds previous decisions in two lower courts.

Monterey County’s administrative office declined to comment. The county did not participate in the Supreme Court appeal, but defended the ballot initiative in court previously.

Monterey County’s ballot initiative, known as Measure Z, was passed in 2016 with 56% of the vote and banned the drilling of new oil and gas drills in the coastal county south of San Francisco. It also banned particular oil production techniques like wastewater injection, which increases pressure in order to extract more oil.

The measure was opposed by Chevron and other fossil fuel industry companies, which challenged the initiative in court two days before it was scheduled to take effect in December 2016. The county then agreed to indefinitely suspend the measure from being implemented while the legal fight proceeded.

Supporters of the initiative have claimed that state law includes statutes that indicate the California legislature never intended to preempt local oil-related ordinances. The court said those statutes only address local authority to restrict where oil and gas activity may occur, not the method by which oil and gas extraction is performed.

The case is Chevron USA Inc. v. County of Monterey, Supreme Court of California, case No. 16CV003978.

For Protect Monterey County: Hollin Kretzmann of the Center for Biological Diversity; Kevin Bundy of Shute Mihaly & Weinberger

For Chevron: Theodore Boutrous of Gibson Dunn & Crutcher; Jeffrey Dintzer of Alston & Bird

(Reporting by Clark Mindock)