Common law
The common lawso named because it was "common" to all the king's courts across Englandoriginated in the practices of the courts of the English kings in the centuries following the Norman Conquest in 1066. The British Empire spread the English legal system to its historical colonies, many of which retain the common law system today. These "common law systems" are legal systems that give great precedential weight to common law, and to the style of reasoning inherited from the English legal system.
Law
Equity is a body of rules that developed in England separately from the "common law". The common law was administered by judges and barristers. The Lord Chancellor on the other hand, as the King's keeper of conscience, could overrule the judge-made law if he thought it equitable to do so. This meant equity came to operate more through principles than rigid rules. For instance, whereas neither the common law nor civil law systems allow people to split the ownership from the control of one piece of property, equity allows this through an arrangement known as a 'trust'. 'Trustees' control property, whereas the 'beneficial' (or 'equitable') ownership of trust property is held by people known as 'beneficiaries'. Trustees owe duties to their beneficiaries to take good care of the entrusted property. In the early case of "Keech v Sandford" [1722] a child had inherited the lease on a market in Romford, London. Mr Sandford was entrusted to look after this property until the child matured. But before then, the lease expired. The landlord had (apparently) told Mr Sandford that he did not want the child to have the renewed lease. Yet the landlord was happy (apparently) to give Mr Sandford the opportunity of the lease instead. Mr Sandford took it. When the child (now Mr Keech) grew up, he sued Mr Sandford for the profit that he had been making by getting the market's lease. Mr Sandford was meant to be trusted, but he put himself in a position of conflict of interest. The Lord Chancellor, Lord King, agreed and ordered Mr Sandford should disgorge his profits. He wrote,