The U.S. Supreme Court signaled its interest in deciding the viability of state laws regulating how companies like Express Scripts and CVS Health reimburse pharmacies for prescription drugs.

The justices April 15 asked the U.S. solicitor general to weigh in on a pending case challenging an Arkansas law governing pharmacy benefit managers.

The U.S. Court of Appeals for the Eighth Circuit struck down the law as preempted by the federal Employee Retirement Income Security Act. Arkansas’ attorney general said this decision conflicts with rulings from the First and D.C. circuits.

The Arkansas Attorney General’s Office issued a statement saying it...