The pared-back industrial relations bill that passed through the Senate this week was a blow to the Hunter's casual mineworkers, the Construction, Forestry, Mining and Electrical Union said.
The union claimed the bill overturned important court decisions that found workers had been unlawfully exploited by mining and labour hire companies.
The Government was forced to strip down its Fair Work Amendment Bill 2021 to get enough support to pass through the Senate on Thursday.
CFMEU Mining and Energy general secretary Grahame Kelly said mineworkers would be bitterly disappointed that, while the bulk of the bill was parked, measures to limit the rights of casuals were passed.
"This government, with the support of One Nation, has introduced an unfair definition of casual based on words in the contract not the reality of the work arrangements," Mr Kelly said.
"Further, mineworkers found to have been unlawfully employed as casuals will be prevented from claiming their rightful entitlements.
"The Federal Court has made a series of sensible judgments exposing the 'permanent casual' rort in the mining industry, which gave hope casual miners exploited over many years.
"The Morrison Government has done the bidding of big business to extinguish that hope."
But One Nation senator Malcom Roberts, whose support secured the bill's success, argued the passing of Schedule 1 of the legislation provided certainty and security for the miners and employers because they now had a casual definition and a legislated right to conversion from casual to permanent status.
"We hope that the casual definition will ensure that abused permanent casual workers, like (Hunter mine worker) Simon Turner, will no longer fall through the cracks in our IR and workers compensation systems for lack of definition," he said.
"Also important is that a worker's right to claim for wage theft has not been removed in the bill."
"Due to the complexity of this legislation we were concerned to ensure there were no adverse consequences, therefore our amendment, which was supported, insists on a detailed review of effects of this legislation for both employers and employees, in 12 months time."
The Minerals Council of Australia expressed its disappointment at the bill's failure to include reforms that would accelerate the approval of enterprise agreements and allow longer greenfields agreements for major projects.
Council chief executive officer Tania Constable described the bill as a lost opportunity.
"It is regrettable that the Opposition, the Greens and some crossbench senators have stifled important regulatory improvements that the nation needs to accelerate post-COVID economic recovery," she said.
"The original bill's measures to accelerate the approval of enterprise agreements and allow longer greenfields agreements for major projects were modest, incremental and overdue changes to boost investment, productivity and prosperity.
"These measures were compromise solutions that emerged from extensive discussions between employers and unions in the industrial relations working groups.
"It is disappointing that much-needed reforms to drive economic recovery have been sacrificed to political expediency."
The Australian Chamber of Commerce and Industry said the bill was a step forward.
"We appreciate the extensive efforts made by the Government to develop the moderate and sensible package of reforms in the IR Omnibus Bill...
"It is important that the Government does not abandon the rest of the Bill and further efforts need to be made over the months ahead to secure support."
