Unions led by the United Steelworkers say the bonuses owed to about 750 current and former Asarco employees have grown in value to more than $10 million, including interest.

A federal judge has ruled that Tucson-based copper miner Asarco LLC must pay millions of dollars worth of bonuses based on the price of copper to union employees in Arizona and Texas.

Asarco, part of Mexico-based mining giant Grupo Mexico, had alleged in a federal lawsuit filed in January 2015 that an arbitrator exceeded his authority by ordering the company to pay a quarterly copper-price bonus to union employees who are not part of the company’s pension plan.

On March 3, Judge Stephen M. McNamee of the U.S. District Court in Phoenix ruled that the arbitrator acted properly, though he essentially rewrote the labor agreement to include the employees in the bonus plan.

The union had contended that both parties failed to recognize that the language in the contract that eliminated pension benefits for new hires would also make new hires ineligible for the price bonus. Asarco did not immediately respond to a request for comment on the ruling.

The issue affects about 550 Asarco employees hired after June 30, 2011, and could cost Asarco upwards of $10 million in back bonus payments, union officials say.

The United Steelworkers leads a group of unions representing more than 2,000 workers at five Asarco locations in Arizona and Texas. The union won the initial arbitration award in December 2014.

Last month, the National Labor Relations Board issued a new consolidated complaint against Asarco for unfair labor practices, including unlawfully implementing parts of its “last, best and final” contract proposal, failing and refusing to bargain, and unilaterally changing working conditions.

The NLRB has scheduled a hearing on March 15, when an administrative law judge will review evidence against Asarco and listen to testimony in the case.

Employees represented by eight unions have continued to work at Asarco’s facilities under the terms of a labor agreement that originally expired in June 2013 but was extended until the parties terminated it in June 2015.


David joined the Star in 1997, after working as a consumer and business reporter in Phoenix for more than a decade. A graduate of Ohio University, he has covered most business beats focusing on technology, defense and utilities. He has won several awards.