How to define the role of trade unions?

This would have been a silly question back in the 1970s when the working class was politically labeled a leading class, when all enterprises big or small were State-owned, and the relationship between workers and their enterprise leaders was not supposed to be that of employees and employers.

This question makes a difference today when the market economy has greatly diversified the ownership of enterprises, and the nature of labor relations is much more complicated than it was when the planned economy dominated the Chinese world of work.