Republican Ohio Attorney General David Yost is suing to stop upcoming trials seen as test cases for forcing drugmakers to pay for societal damage inflicted by the opioid epidemic.
Yost says attempts to force drugmakers to pay should come in a single state action to allow equal distribution of money across Ohio.
Yost said allowing counties to go to trial individually could lead to inconsistent damage awards and some counties receiving nothing if they lose in court.
The trials, involving claims brought by Cuyahoga and Summit counties, are scheduled for October.
Akron Mayor Dan Horrigan, a Democrat, said Yost's filing ignores local governments' "constitutionally protected interests" in seeking justice for taxpayers.