Johannesburg — Collective agreements apply to all employees, even members of minority unions, the Labour Court in Johannesburg heard on Thursday.
"Collective agreements bind all employees, including members of the minority union," Anton Myburgh SC, for the Chamber of Mines, said.
The Association of Mineworkers and Construction Union's (Amcu's) argument had no substance, he argued.
Amcu is opposing a bid by the chamber to have an interim court order preventing it from striking in the gold sector made permanent.
Myburgh argued that Amcu was part of wage negotiations in the gold sector for a month before the chamber declared a dispute with it.
The chamber approached the court after Amcu served strike notices to employers in the gold and platinum sector on January 20.
At that time, a wage agreement in the gold sector was signed with the National Union of Mineworkers (NUM), Solidarity, and the United Association of SA.
The agreement was extended to Amcu, which the union said was invalid.
Amcu members in the platinum mining sector have been on strike since January 23 demanding a minimum monthly salary of R12,500.
They have rejected the employers' offer that would bring their cash remuneration to R12,500 by July 2017.
The NUM is the dominant trade union in the gold sector while Amcu is dominant at platinum mines.