A contract of employment is a category of contract used in labour law to attribute right and responsibilities between parties to a bargain. The contract is between an "employee" and an "employer." It has arisen out of the old master-servant law, used before the 20th century. But generally, the contract of employment denotes a relationship of economic dependence and social subordination. In the words of the controversial labour lawyer Sir Otto Kahn-Freund, "the relation between an employer and an isolated employee or worker is typically a relation between a bearer of power and one who is not a bearer of power. In its inception it is an act of submission, in its operation it is a condition of subordination, however much the submission and the subordination may be concealed by the indispensable figment of the legal mind known as the 'contract of employment'. The main object of labour law has been, and... will always be a countervailing force to counteract the inequality of bargaining power which is inherent and must be inherent in the employment relationship."