JACKSON, Miss. — Rural water systems say the Mississippi Public Service Commission overstepped its authority when it required a 60-day delay in utility deposits for domestic violence victims.

Jim Herring, a lawyer for the water systems, argued Monday to the state Supreme Court that the commission illegally tried to regulate rates when it made the rule in 2014. Herring also says it is illegal under a 2013 law barring the commission from regulating internal affairs of any water association, electric cooperative or municipal utility.

“They exceeded their statutory authority when they adopted this rule,” Herring told a three-judge panel led by Presiding Justice Jess Dickerson on behalf of the Mississippi Rural Water Association.

Assistant Attorney General Frank Farmer asked the court to ratify an earlier decision by a Hinds County chancery judge that found the rule legal. A federal judge also dismissed a lawsuit by the rural water group, saying the rule didn’t conflict with federal law protecting a water association’s revenue and that the commission couldn’t be sued in federal court over the question.

The suit is the latest clash over the commission’s ability to regulate water associations and electric cooperatives.

Farmer told justices that the Public Service Commission was within its legal authority and was not improperly regulating rates. The commission isn’t allowed to set rates for nonprofit or municipal utilities.

“A deposit is just not a rate,” Farmer said. “It’s just not.”

Herring disagreed, noting that the commission takes deposits into account when calculating whether rates sought by investor-owned utilities such as Entergy Mississippi are appropriate. He also said changing deposits would alter an association’s ability to collect bad debts.

“This is an easy call,” Herring said. “When you look at that definition of rates, it’s very broad.”

Farmer said the commission can consider other things in ratemaking cases without all those considerations becoming part of a rate.

“A rate is generally paid to a utility for a unit of some good,” Farmer said. “In this case, it’s a unit of water. We’re not telling them how to set those rates.”

The commission in recent years has made multiple moves to impose rules on water associations and electric cooperatives besides the domestic violence rule. Other disputes have centered on energy efficiency programs, rates paid to people who own solar panels and billing disputes.

Earlier this year, the commission and electric cooperatives agreed on a law that explicitly limited some of the commission’s powers over cooperatives, including the commission’s power to force cooperatives to make certain payments to solar panel owners. The move came after lawmakers introduced multiple bills that would have revoked any commission authority over electric cooperatives. The compromise bill specifically allowed the commission to regulate deposits for victims of domestic violence.

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