The Federal Court has ordered a union to end any alleged involvement in a blockade at a Melbourne Water treatment plant at Werribee, in Melbourne's outer-west.
However, the blockade which is manned by dozens of unemployed local tradesmen protesting over the hiring of four Filipino workers on 457 visas, is allowed to continue.
Justice Shane Marshall said the injunction can only apply to the alleged involvement of the Australian Manufacturing Workers Union (AMWU) in the blockade.
"The judgement is not about the rights and wrongs of the employment of such persons," he said.
"It is also not about the rights and wrongs of action taken by community protesters."
The AMWU denies any direct involvement in the ten-day blockade of the $40 million water treatment plant.
Earlier this week, the Fair Work Building and Construction Inspectorate took court action to try to stop the picket that it said was co-ordinated by the AMWU and union organiser Tony Mavromatis.
The court heard an industrial relations consultant hid a recording device in her bra, in a bid to link AMWU to the blockade.
A lawyer for the inspectorate told the court the AMWU and Mr Mavromatis were trying to coerce a labour hire company to sack the Filipinos and hire the unemployed men in breach of the law.
But the union's lawyer said Mr Mavromatis was only acting as a conduit for the parties at the request of Grace Collier, a consultant for the head contractor, Tedra Australia.
Justice Marshall ruled a trial over the part played by the union will be held next month.
Previously the judge question the behaviour of Ms Collier.
"Did she think she was in a James Bond movie or something?" he said.
Tedra Australia estimates that it has suffered $1.5 million in losses because of construction delays.