But the trip to The Greenbrier was not out of line with what the conferences typically cost, he said.
"I realize that having this conference at The Greenbrier raises some red flags," Plants said. "But this expense is unavoidable."
"I have to keep my lawyers licensed," he added.
Commission President Kent Carper was not critical of the trip.
He said the cost was not extravagant and the prosecuting attorney must pay for continuing education classes.
Carper has heard some whispered complaints around the courthouse, he said.
"When people say they had it at The Greenbrier, then other people do get upset," Carper said. "But no one seems to get upset when they go to other resorts for training."
Carper added that anyone wishing to pursue the point could do so in the commission office.
"If someone makes a formal complaint, then I'll look at it," he said.
Carper thinks all of the attorneys at The Greenbrier during the conference were there for "good solid reasons."
"I have no reason to believe they weren't," he said.
The county commissioners must approve every elected official's budget.
Plants had $15,000 allocated toward continuing education and $15,000 to travel.