Johnny "Doc" Dougherty wants a judge to dismiss a dozen charges in the 116-count indictment filed against him, the councilman and others.
The January indictment accuses Dougherty of keeping Councilman Bobby Henon on the payroll to push the electrician union's agenda at City Hall.
In a motion filed Wednesday, defense lawyer Henry Hockeimer argues that council members can have outside jobs and says it wasn't illegal for Henon to push union causes. Neither federal prosecutors nor Henon's lawyer returned calls for comment Thursday.
Dougherty leads the local electricians union and the city's Buildings Trades Council.
Henon, a Democrat, remains on the council. Prosecutors say he earned about $200,000 a year from the two jobs.