Former court supervisor William Hird pleaded guilty Monday to 18 counts of mail and wire fraud and lying to investigators.
A federal judge will determine his sentence later. Guidelines call for a sentence of about 12 to 18 months.
Authorities have portrayed the traffic court as a pit of patronage and corruption. Nine judges were charged with dismissing or reducing citations for friends, relatives, business associates and political allies.
Three judges involved in the case pleaded guilty earlier. Six defendants, including several former judges, are awaiting trial.
In the wake of the indictment, the traffic court has been abolished and its functions are handled with the city's municipal court.