Court keeps 9.98% MISO rate in place, limiting refunds

The D.C. Circuit left the 9.98% return used in the Midcontinent Independent System Operator, or MISO, transmission dispute in place on June 5, 2026, shutting down Louisiana regulators’ latest bid to reopen the fight. For electric customers on the regional grid, that means the benchmark rate still feeds disputed charges, and the refund question does not get a fresh reset.

The benchmark that keeps driving the bills

The court said its earlier MISO Transmission Owners decision controls here: the Federal Energy Regulatory Commission, or FERC, must apply the return in effect when it makes a decision, including in related proceedings. On that view, Louisiana’s challenge to FERC’s use of the 9.98% return was foreclosed by the law-of-the-case doctrine, rather than reopened for another look at the merits.

That matters because the 9.98% figure is not just a number in a legal fight. It is the benchmark feeding into transmission charges on the MISO grid, so keeping it in place affects what customers may pay or get back on disputed bills.

A narrower path to refunds

The transmission owners also ran into a separate barrier. The court said they lacked Article III standing to challenge FERC’s consideration of a successive complaint because they did not show redressability for one claimed injury or imminence for another.

That standing ruling does not erase the underlying rate fight, but it does shrink the remaining route to another round of refunds tied to the disputed return.