How much do DeKalb County taxpayers owe former Gov. Roy Barnes?

That's a question that county commissioners want Barnes to answer before he files another lawsuit — following one earlier this month — on DeKalb's behalf.

Commissioners already gave the go-ahead on the first lawsuit which Barnes, now a private attorney, filed July 10. That lawsuit challenges a state law that could change the way county sales tax revenue is shared with cities, including the newly approved city of Dunwoody.

Now, a proposal by south DeKalb commissioner Lee May is pushing another lawsuit, or maybe even two, that would challenge last week's incorporation vote in Dunwoody and strip the new north DeKalb city of the tax-rich Perimeter Community Improvement District within its boundaries.

Losing the Perimeter businesses could cost DeKalb millions of tax dollars. May said the county law department told him DeKalb would prevail in court. "I was told verbatim that it's a no-brainer," he said at Tuesday's commission meeting.

But other commissioners said Barnes told them to expect a "costly and protracted" battle with an uncertain outcome. It's unclear how costly, because Barnes hasn't filed a bill since he was hired in April 2007.

The commission voted secretly back then to approve the lawsuit over sales tax sharing. After that unanimous vote, which is documented in confidential meeting minutes obtained by The Atlanta Journal-Constitution, the county law department signed a contract for Barnes' legal services.

Commissioners Burrell Ellis of central DeKalb and Elaine Boyer of north DeKalb said they didn't know the former governor had been hired until he met with the commission in a closed-door meeting in May.

"I was shocked the day Gov. Barnes walked in," Boyer said.

Ellis said the meeting with Barnes lasted 45 minutes or less — only enough time for a broad legal review. "He has some good legal theories, but he also believes this will be costly and protracted," Ellis said. Before approving additional lawsuits, Barnes should tell commissioners more about the legal strategies and risks, Ellis said — and about the money that Barnes is already owed.

"I would suggest that the governor bring that bill when he comes to meet with us," Ellis said.

Commissioners voted 5-2 Tuesday to delay a vote on additional lawsuits until Aug. 26.