Some 72 gondoliers who blocked Venice's Grand Canal in a series of protests between 2003 and 2005 are facing a total of 173 years in jail.
Prosecutors accused the gondoliers, who were demonstrating against a restriction in working hours, of mounting a ''naval blockade''.
Defence lawyers said this charge was not applicable because the protests took place on an inland waterway.
They also noted that the gondoliers let water buses through.