The Federal Court has thrown out a union’s challenge to new rules that make it easier to hire foreign workers on offshore rigs.

The Maritime Workers Union has taken action against to measures introduced by the LNP Government, which was built on a Labor Government change to the Migration Act.

Labor extended the ‘migration zone’ in the Act to cover offshore oil and gas platforms, and the current Federal Government has sought to further extend the range of visas covered by the act, so that more foreign workers would not need to obtain a permanent visa.

But that change was disallowed by the Senate, and so Assistant Minister for Immigration Michaelia Cash has used a ‘legislative instrument’ to invalidate the amendments to the act.

The MUA was arguing that the Federal Government could not actually use the legislative instrument as it had, but the Federal Court ruled that it could.

But the judgement did specifically state that the union argument “is a powerful one.”

“At one level it seems almost instinctively correct,” the document reads.

The Australian Mines and Metals Association (AMMA) has welcomed the ruling, saying the complicated legal manoeuvres by the MUA were an attempt to hold the reins on an industry that it had not previously been able to touch.

AMMA chief executive Steve Knott says it will restore some certainty to the offshore resource industry.

“The offshore resource sector uses a very small number of non-Australian specialists, but has created 70,000 jobs in Australia and injected $200 billion into our economy,” he told the ABC.

“It is well beyond time that some sensibility is restored in this area and Australia's oil and gas operators can get on with creating jobs and economic value for our country.”

MUA national secretary Paddy Crumlin opened fire on the Government and AMMA.

“The majority of Australian Senators voted to disallow the Abbott Government's attempts to open the floodgates to foreign workers in the offshore oil and gas sector,” he told reporters.

“That's before the decision was steamrolled by Michaelia Cash.

“[Unions] believe Australian maritime workers should have the right to work in their own country and the ideological warriors in the Abbott Government and Australian Mines and Metals Association are seeking to take out an entire Australian industry,” he said.