A contract of employment is a category of contract use in labour law to attribute right and responsibilities between parties to a bargain. On the one end stands an "employee" who is "employed" by an "employer". It has arisen out of the old master-servant law, used before the 20th century. Put generally, the contract of employment denotes a relationship of economic dependence and social subordination. In the words of the influential labour lawyer Sir Otto Kahn-Freund,