SCANA Energy gained a key ally Friday — a federal judge — in its fight against state regulators' accusations it overcharged customers.

And the timing couldn't have been better for the natural gas marketer.

Starting Tuesday, SCANA officials are scheduled to go before the Georgia Public Service Commission about whether it was wrong to charge some customers higher rates than others for the same gas plan. Another company, Georgia Natural Gas, previously settled similar charges and agreed to a hefty rebate.

SCANA decided to take the fight with the PSC to the end, at the same time customers sought to band together in federal court in Atlanta and sue the company for triple damages.

But in a ruling Friday, U.S. District Judge Beverly Martin dismissed the customer lawsuit. Though the company last year did not actively offer a new, lower rate to existing customers, it was published on the company's Web site.

"Those rates were clearly within the public domain and readily accessible" to customers, she wrote.

Paul Quiros, an attorney for SCANA, said in a statement that the ruling supports SCANA's case before the PSC next week.

"This order completely vindicates SCANA Energy with regard to the claims brought by these customers," Quiros said. "[W]e are confident we will prevail in those hearings for the same reason we prevailed in federal court: because we have done nothing wrong," said Quiros, an attorney with King & Spalding.

PSC members Friday said it was too early to tell whether the court ruling would influence them.

"I don't think just because a federal judge throws it out that we end the case at the PSC," Chairman Chuck Eaton said. "I have to talk to the staff and the PSC and see where everything stands."

PSC staff began investigating SCANA's practices in December after receiving 24 complaints, 14 from existing customers, about the gas marketer's variable rate plans, according to filed testimony.

SCANA began offering a new standard variable-rate plan in March 2007 but left existing customers on the previous, higher-priced plan. The gas marketer did not tell existing customers about the new plan, according to PSC staff testimony.

The old customers could have been charged as much as $108.98 more than the new customers, the agency staffers said. Officials have never disclosed how many customers were affected; the number has been redacted from documents in the state proceedings.

"SCANA's activities could serve and did serve to mislead the public," staff said in PSC documents.

SCANA officials call staff's allegations "erroneous." In testimony filed with the PSC, they said SCANA has published the prices for each variable-rate plan and updated its Web site monthly with prices for current plans as well as ones that no longer existed.

GNG, owned by AGL Resources, agreed in March to issue $25 credits to affected customers. The PSC recently notified GNG customers that anyone who switched to a variable- or fixed-rate plan before July 31 would be eligible for a $25 credit. Those customers would have to notify GNG that they qualify for the credit, which will be issued in August.

At the time of GNG's settlement, SCANA officials vowed to keep fighting.

Attorneys for SCANA have tried a number of different legal tactics to help the company's case. In April, the company was denied a request to question the PSC staff before next week's hearing. SCANA then tried unsuccessfully to use the state's open-records law to get certain documents from the PSC.

"SCANA's counsel has taken an exceptionally aggressive posture in this case and has taken extreme liberties with the standard procedures that the commission has followed for years," PSC member Robert Baker said Friday. "The commission has accommodated those changes and is moving forward with the case and is anticipating that we'll go forward with the hearing."

THE STORY DO FAR:

Previously: The PSC staff accused SCANA Energy of overcharging some customers last year.

The latest: A federal judge dismissed a lawsuit against SCANA, saying the gas marketer published its rates monthly.

What's next: SCANA will go before the PSC on Tuesday and Wednesday to defend its business practices.