Mississippi Power & Light Co. v. Mississippi Ex Rel. Moore

1988-06-24

Headline: Federal order requiring a Mississippi utility to buy a one-third share of high‑cost nuclear power is upheld, blocking the state from reexamining that purchase and making customers responsible for federally allocated costs.

Holding: The Court ruled that a federal agency’s allocation of Grand Gulf wholesale power pre-empts the state commission from conducting a prudence review, and the utility must treat the FERC-mandated payments as reasonable operating expenses.

Real World Impact:

Prevents state regulators from blocking recovery of FERC-mandated wholesale costs.
Requires the utility to treat FERC-ordered Grand Gulf payments as reasonable expenses.
Limits state ability to conduct prudence reviews that would deny cost pass-through

Topics: utility rates, federal preemption, nuclear power costs, state utility regulation

Summary

Background

A Mississippi electric company agreed to take part in building and operating Grand Gulf Unit 1, which began commercial operations on July 1, 1985. The federal energy agency (FERC) reviewed agreements among related utilities and ordered that the Mississippi utility purchase about 33% of Grand Gulf’s output at rates FERC found just and reasonable. The state public service commission later adjusted retail rates to help the company recover Grand Gulf costs, and Mississippi officials appealed, asking the state supreme court to require a state prudence review of the construction and purchase decisions.

Reasoning

The Supreme Court considered whether the federal FERC proceedings and allocation pre-empted a state commission’s prudence review. Relying on prior decisions about federal control of wholesale rates, the Court held that FERC’s allocation and rate determinations govern interstate wholesale transactions. The Court concluded that states may not “trap” or refuse to recognize costs that FERC has ordered as just and reasonable. As a result, the state may not conduct a prudence inquiry that would deny recovery of FERC‑mandated wholesale costs in setting retail rates.

Real world impact

The ruling means state regulators must treat FERC‑mandated wholesale payments as reasonable operating expenses when setting retail rates, preventing states from using prudence reviews to force refunds or block cost pass‑through. Challenges to the fairness of FERC’s allocation remain for FERC itself or courts reviewing FERC, not for state rate proceedings.

Dissents or concurrances

A concurrence emphasized deference to FERC’s jurisdiction over interstate pools; a dissent argued states should still be able to review whether a retail utility prudently chose to join the project.