Transcript from ABC Lateline Report

EMMA ALBERICI, PRESENTER: The Maritime Union wants the Federal Government to close a legislative loophole that allows an overseas company to employ foreign workers in Australian waters without 457 visas.

Allseas is laying the pipeline for a natural gas project off the coast of WA. 

The Federal Court has ruled Allseas does not need to obtain 457 visas for its 125 overseas employees. 

Unions vented their anger at a rally in Perth today, as Amy Bainbridge reports.

AMY BAINBRIDGE, REPORTER: The Maritime Union wants to send a message to energy giant Chevron and the Swiss company contracted to it, Allseas. The MUA is angry about a Federal Court decision allowing Allseas to use foreign workers to lay gas pipeline on the Australian seabed without using 457 visas.

CHRIS CAIN, WA BRANCH SECRETARY, MUA: Just to bring workers in and exploit them workers and not pay them the Australian wages and conditions, as it's just come down through the Allseas decision, is an absolute disgrace to humanity.

AMY BAINBRIDGE: Chevron's ambitious Gorgon project is tapping into gas reserves under the seabed - 130 kilometres off the northwest coast of Western Australia. The gas will then be piped to Barrow Island. 

In the Federal Court in Perth, Allseas successfully argued their employees on two boats are not working in Australia's migration zone, and don't need work visas. 

It argued the two boats laying the pipeline were not permanent resource installations, fixed to the Australian seabed, and therefore could bypass the need for visas.

GILLIAN TRIGGS, UNIVERSITY OF SYDNEY: I was initially a little surprised because I felt that Australia had a clear right to regulate a resource activities of that kind on the territorial sea, or on the continental shelf, but when you look at the legislation in detail and look at the reasoning of the judge, one can be very sympathetic with the reasoning that underlay the decision.

AMY BAINBRIDGE: The union says the Government must change legislation so other companies don't exploit existing laws.

PADDY CRUMLIN, NATIONAL SECRETARY, MUA: I mean, something has to be done. If it's not done, here is one of the most lucrative, productive and important industries to Australia, that is effectively locking out Australian workers from involving themselves into it because of a technicality in a piece of legislation. That needs to be addressed, it needs to be fixed, and needs to be done urgently.

GILLIAN TRIGGS: We may need to review the current legislation to see whether it really is keeping up with the realities of technology. But also with the realities that in some areas there will be expert skills that will come internationally, and how we regulate that.

AMY BAINBRIDGE: The Federal Government is still reviewing the court decision. Amy Bainbridge, Lateline.

EMMA ALBERICI: And Lateline contacted Allseas for a comment but the company declined to issue a statement.