WASHINGTON  — The Supreme Court on Thursday rejected a nationwide settlement with OxyContin maker Purdue Pharma that would have shielded members of the Sackler family who own the company from civil lawsuits over the toll of opioids but also would have provided billions of dollars to combat the opioid epidemic.

After deliberating more than six months, the justices in a 5-4 vote blocked an agreement hammered out with state and local governments and victims. The Sacklers would have contributed up to $6 billion and given up ownership of the company but retained billions more. The agreement provided that the company would emerge from bankruptcy as a different entity, with its profits used for treatment and prevention.

Justice Neil Gorsuch, writing for the majority, said “nothing in present law authorizes the Sackler discharge.”

Chief Justice John Roberts and Justices Brett Kavanaugh, Elena Kagan and Sonia Sotomayor dissented.

“Opioid victims and other future victims of mass torts will suffer greatly in the wake of today’s unfortunate and destabilizing decision,” Kavanaugh wrote.

The high court had put the settlement on hold last summer, in response to objections from the Biden administration.