The misuse came to light in 2004 when an employee helped leak information to the media during a heated race for Milwaukee mayor that a candidate, acting Mayor Marvin Pratt, was often behind in paying his heating bills. Pratt lost to the current mayor, Tom Barrett.
Pratt said he's convinced the disclosure cost him votes and unfairly damaged his reputation. Pratt said he recently met with top company executives and was satisfied it has stopped the problem as much as possible. He said he has dropped earlier plans to explore a lawsuit.
"They caught this and they are making corrections to it, which they should. But it never should have happened in the first place. Not just to me, but to anyone. They gave their employees too much latitude to access files."
After the incident involving Pratt, the company fired the employee who leaked the information and vowed to crack down after finding others engaged in similar practices. But problems continued.
In all, the utility fired or disciplined at least 17 employees for breaking the policy between 2005 and 2007, according to testimony and company records. Another employee gained access to Pratt's account for no business purpose and was suspended in 2005 but kept her job.
Others looked up information on their bosses at WE Energies and local conservative radio host Mark Belling, who said he had never been told of the breach.
Ponemon said employees with access to vast amounts of customer information often see nothing wrong with looking up an individual out of curiosity, or in some cases, more sinister motives.
Governmental agencies have also struggled with the problem.
The IRS took 219 disciplinary actions, including firings and suspensions, against employees who browsed through confidential taxpayer information last year, according to the U.S. Treasury Inspector General for Tax Information. That was more than double the number the previous year.
Last month, the Minnesota Department of Public Safety said it disciplined two employees who accessed information on 400 residents from its driver's license database. The agency did not say what the discipline was because it continues to investigate. It said the employees were looking for their own entertainment, not any criminal motives.
WE Energies serves 1.1 million electric customers in Wisconsin and Michigan's Upper Peninsula and 1 million natural gas customers in Wisconsin.
Shafer said in an interview that the utility took steps to eliminate the practice and only one employee has been disciplined for violations in the last year.
After the 2004 incident, the company started checking who accessed high-profile customer accounts and requiring annual training on its policies.
Still, Shafer acknowledged in her deposition last year that it would be "difficult, if not impossible" to discover many instances of misuse.
Utility regulators in Michigan and Wisconsin said they had not been notified of the company's problems. They say they do not have any rules covering such misuse.
The head of the Wisconsin Citizens' Utility Board, which lobbies on behalf of utility customers, said he was "shocked and dismayed" to learn about the practice.
"The testimony is incredibly candid. I'm very surprised that utility employees were misusing this information," said executive director Charlie Higley. "We hope WE Energies has taken steps to ensure that information is treated privately."