RALEIGH, N.C. (AP) — Pressure could increase on North Carolina utilities regulators to justify decisions to charge customers hundreds of millions of dollars more as part of a case the Supreme Court heard Tuesday.

State Attorney General Roy Cooper’s office argued that there’s little evidence the North Carolina Utilities Commission independently analyzed the consumer impact of allowing Duke Energy to raise electricity rates for its 1.8 million customers by 7.2 percent. The commission is responsible for balancing the interests of both customers and investors in what are regional monopolies, while ensuring the companies are healthy enough to maintain a system of constant electricity supply.