The peculiar nature of labour is the fact that it involves the services of human beings and does not permit the economists to rely on normal tools of economic analysis.
The economist must also examine the institutions such as employer worker organisations that have been created by human beings, to see how they affect the working of the labour market.
Therefore with respect to human beings and organisational behavior, the economists have to depend on other disciplines like sociology, psychology, history and political science and relate them to the basic economic questions.
In a privately organized economic system labour is allocated and its price is determined through the institution of a free labour market. In this labour market each labourer is free within limits of his needs and abilities, to select the occupation at which he wants to work, to chose the firm in which he wants to work and even to decide whether he wants to work or not.
Moreover he may decide to quit his present job and seek a different one. He may decide to move from one part of the country to another, as he sees fit. Since there are no internal passports to restrict his mobility, he only needs to find some other employer whois willing to hire him.
However, this was not always so. Unfree labour once existed.