Sibanye Gold Ltd. and the Association of Mineworkers and Construction Union headed to labor court Dec. 18 to fight over the legality of a nearly monthlong strike.

The court's ruling is set to decide whether AMCU has the legal right to strike and, by extension, if Sibanye Gold can impose a wage agreement on all workers.

AMCU workers walked off the job Nov. 21 after its member opposed a wage agreement Sibanye Gold reached with other unions representing workers at its gold mines in South Africa.

Initially, there was no question that AMCU had the right to strike. But in recent days, Sibanye Gold tried to extend the wage agreement to all workers, including AMCU members, after it said union membership numbers in favor climbed over 50%, allowing it to make the agreement binding. In a Dec. 13 news release, it told striking workers to return to their jobs Dec. 15.

"If the court rules in our favor, the strike will not be protected, which means it will be an illegal strike," James Wellsted, Sibanye Gold's head of investor relations, told S&P Global Market Intelligence. "At that point, we'll be able to take disciplinary action, which could include dismissal."

Sibanye Gold will have to show documentation related to its tally of union members, which it has said gives it the right under labor laws to impose the wage agreement on AMCU workers, Wellsted noted. He said he expects the court, which adjourned Dec. 18, to make a decision later this week.

Platinum strike?

It is unclear how AMCU, which has cast doubt on Sibanye Gold's union count, would react to such a ruling. In response to Sibanye Gold's demand that workers return to work Dec. 15, AMCU said it would not back down.

"There is nothing that the employer will do to us that we will not challenge," AMCU tweeted Dec. 15.

AMCU President Joseph Mathunjwa has also said the union would fight on and called into question the power of the courts over the strike. "To strike is our constitutional right, so Sibanye cannot use the court for them to enslave the black majority mineworkers," Mathunjwa said in an interview with Moneyweb, a South African business publication.

In the interview, he also said, as before, that he might try to expand the strike into Sibanye Gold's platinum operations. "Wherever Froneman has got a business interest, he will see the might of AMCU members in South Africa," Mathunjwa said, referring to Sibanye Gold CEO Neal Froneman.

So far, neither Sibanye Gold nor AMCU have budged on their positions over the wage agreement. The union, which took part in negotiations, has said it was not enough, while Sibanye Gold has said it would not sweeten the deal.

The strike has turned violent, with three deaths linked to the labor action as of late November.