A Victorian court has extended a ban preventing the disruption of freight on the Spirit of Tasmania when it docks in Melbourne.
The company Qube Ports has taken legal action over a picket line at Station Pier at Port Melbourne.
The protest began in June as part of an industrial dispute over the sacking and suspension of workers, and has disrupted freight movement on the TT-Line ferry, the Spirit of Tasmania.
Lawyers for Qube Port claim the Maritime Union is orchestrating the picket line, something the union denies.
A judge has agreed the issue over the union's involvement should go to trial.
A court order preventing any further disruption of freight to and from Tasmania has been extended, but the order does not stop the workers' protest.
The Premier, Lara Giddings says it is an unusual situation, because the action is not publicly supported by the Maritime Union.
"Therefore the normal processes that are in place under Fair Work Australia cannot be put into place," said Ms Giddings.
"The fact that this is a civil protest about some very genuine industrial issues makes it very difficult for us and we really rely on the courts here."
The Spirit of Tasmania II is due to dock in Melbourne again on Friday morning.