A situation in which the workers in a country are unable to form and join trade union organizations of their own choosing for the protection of their interests, is contrary to generally recognized principles relating to freedom of association. Sometimes freedom of association is denied on the basis of occupation, sex, colour, race, beliefs, nationality, political opinion, etc, not only to workers in the private sector of the economy but also to civil servants and employees of public services in general. Even if freedom to establish trade unions has long been recognized in a great many countries, authorization to establish associations is not in itself sufficient to guarantee their effective development, due to restrictions such as single trade unions, government favouritism of a trade union, or compulsory union membership.
The development of trade unions, largely a product of the Industrial Revolution, began in England in the 1820s and by the late 19th century, had spread to most of western Europe. Significant efforts to form workers' associations were made in the 1920s and 1930s in Latin America, particularly among rural workers, and after the Second World War in Africa and Asia. In contrast to the situation in Europe, in the developing countries the organization of rural workers, largely employed in the European-imposed plantation system of agricultural production, preceded or paralleled the organization of urban workers. The formation of trade unions provoked the reaction of employees and governments; it was only after World War II that trade unions were recognized as key partners in modern labour relations.