Through the combination of social and economic change, trade union organizations experience greater difficulty in carrying out their task of representing the interests of workers, partly because Governments, for reasons of economic utility, often limit the freedom or the negotiating capacity of labour unions. Hence traditional networks of solidarity have more and more obstacles to overcome. The repeated calls issued within the Church's social doctrine, beginning with Rerum Novarum[60], for the promotion of workers' associations that can defend their rights must therefore be honoured today even more than in the past, as a prompt and far-sighted response to the urgent need for new forms of cooperation at the international level, as well as the local level.