In a split decision, the California Supreme Court on Wednesday declined to review a state appeals court ruling against major manufacturers of lead paint that held them liable for hundreds of millions of dollars in remediation costs to remove the dangerous product from homes.

The decision leaves in place a ruling by the Sixth District Court of Appeals last November, which concluded that Sherwin-Williams Co., NL Industries Inc. and ConAgra Grocery Products Co. “must have known” that lead paint posed a risk of serious harm to children even while they promoted its sale.

According to the case docket, Justices Goodwin Liu and Leondra Kruger had argued that the company's petition for review should have been granted.

The appellate court mostly upheld a $1.15 billion judgment by a Santa Clara County trial court against the paint manufacturers but curtailed the scope of homes to be included in the remediation fund to those built before 1951. The California cities and counties that brought the case, led by Santa Clara County, sought to include homes built prior to 1981.

“This is a major victory for California children and families. It settles all of the state law issues in this case,” said Dennis Herrera, the city attorney for San Francisco, in a statement on Thursday. “These companies have dragged out this case for 18 years. It's past time that they stop shirking their responsibility and start paying to clean up the toxic mess they created. We don't need another generation of children to be poisoned by their product.”

But the litigation may still go on for some time. In an interview Thursday, Bartlit Beck Herman Palenchar & Scott partner Andre Pauka, who represents NL Industries, said the company plans to appeal to the U.S. Supreme Court.

“We're disappointed that the California Supreme Court didn't accept our petitions, because we think the appellate court decision was unfair and unprincipled,” Pauka said. He called the appellate court decision an “unprecedented expansion of public nuisance law.”

Attorneys for Sherwin-Williams and ConAgra—represented by the firms Jones Day and Reed Smith, respectively—did not immediately respond to requests for comment on Thursday morning. But in a joint statement, all three companies said they plan to seek review by the U.S. Supreme Court and characterized the California appellate court's decision as an outlier.

“Public nuisance cases filed in seven jurisdictions—Ohio, Rhode Island, Missouri, New Jersey, Illinois, New York and Wisconsin—have all been either rejected by courts, or by a jury or voluntarily dismissed,” they said in the release.

The companies are also pushing a California ballot measure that would shoulder taxpayers with the costs of cleaning up lead paint and other home environmental hazards. The “Healthy Homes and Schools Act” would place a $2 billion bond on the November ballot.

“This is an appalling abuse of the initiative system to try to avoid a judgement and try to shift the burden to taxpayers,” Santa Clara County Counsel James Williams said Thursday. He called the resolution of the case by the California Supreme Court “long overdue.”

Should the case eventually go back to the trial court, it will have to determine the proper amount of the remediation fund in light of the appellate court ruling and who should be in charge of administering it. Pauka said he believes that appellate court's decision would limit the size of the fund to around $400 million dollars, less than half of the original figure.

Joseph Cotchett of Cotchett, Pitre & McCarthy, which represented the California cities and counties along with the firm Motley Rice, said on Thursday he would push to start proceedings back at the trial court “as quickly as possible.”

“We want to move ahead,” he said. “It's about time that 18 years of litigation that they have delayed, delayed has come to an end.”