The head of one union that represents about 1,600 county employees said the county blindsided union leaders with a currently before the Maryland General Assembly.
"I don't see how any union leader can support this because it changes the terms and conditions of employment and should at least be brought to the unions first," said John Ripley, president of the Baltimore County Federation of Public Employees.
The union counts sheriff's deputies and correctional officers among its members.
County officials say the bill could by overturning a court ruling that said it was charging too much for a penalty on interest on pensions to retirees who transferred their state pension time into the county retirement system.
"We had no idea this was coming," Ripley said. "It was a surprise."
The Baltimore County Federation of Public Employees is still scrambling to understand the full impact of the bill and determine how many members might be affected. Preliminary numbers gathered by the state chapter of the union suggest the bill would "be much higher than the 150 (the county) is using," Ripley said.
Not every union, however, opposes the bill.
Michael Day, president of the Baltimore County Professional Fire Fighters, testified Tuesday before the House Appropriations Committee in favor of the bill.
Day also sits on the Board of Trustees of the Employees' Retirement System.