FERC Chairman Willie Phillips defended the commission’s transmission planning rule after the court eliminated the Chevron deference for federal agencies.

The energy sector faces uncertainty following back-to-back U.S. Supreme Court decisions that limit federal agency authority for new rules and sharply extend the statute of limitations for filing suits for existing regulations under the Administrative Procedure Act, according to ClearView Energy Partners.

The Supreme Court on Friday struck down the Chevron doctrine in Loper Bright Enterprises v. Raimondo and on Monday said plaintiffs can sue over regulations for up to six years after they are affected by them, instead of six years after they take effect, in Corner Post v. the Board of Governors of the Federal Reserve System.

“To the extent that uncertainty can quash investment and impair return, we would suggest that Loper Bright could have significant implications for U.S. energy infrastructure on its own,” ClearView said Monday in a client note. “And, to the degree that Corner Post provides a means for reopening (or extending) disputes, we think it could increase the amplitude and frequency of future policy flux.”

Under Chevron deference, investors may have generally assumed that new agency rules were largely durable, the research firm said. Now, they may wait to invest until judicial reviews are completed, and regulated entities’ may forgo early compliance with anticipated or pending regulations, ClearView said.

“This is going to inject a heightened level of litigation in courts, extraordinary uncertainty in the coming years as to what is permissible and what is not as far as establishing rules and promulgating rules, and will likely hamstring an agency’s ability to move quickly,” Basil Seggos, a Foley Hoag partner, said Tuesday.

The decisions could lead states to take a more expansive regulatory role, creating a growing patchwork of rules across the country and increased uncertainty for regulated entities, he said.

The Chevron doctrine, established in a 1984 Supreme Court decision, held that in cases where a federal statute is ambiguous, courts must give federal agencies deference in their interpretation of the law, as long as the interpretation is reasonable. It has been cited more than 18,000 times in federal court decisions, making it the most cited administrative law case in history, according to Varu Chilakamarri, a K&L Gates partner.

Keep reading at Utility Dive

For more on the interaction of the government and the utility industry, check out the DoE’s efforts to enhance the grid, more discussion on the Supreme Court’s Chevron decision, and the DoD partnering with Duke Energy.