The critical way, I think, and the only sustainable way, really, to ensure that supply chains are transparent is through freedom of association in the supply chains. A major garment company has recently stated that the only ethical way to ensure ethical business is to ensure that you have freedom of association all the way through your supply chain. That would mean establishing monitoring systems of the workers themselves and of the supply chains. Increasingly, global framework agreements between multinationals and trade unions are recognizing that and using it as a model.
On November 30th, 2017. See this statement in context.