Equity is a body of rules that form an appendage or gloss to the general rules of law . It represents the attempt , in origin at least , of the English legal system to meet a problem which confronts all legal systems reaching a certain stage of development.
To ensure the smooth running of the society, it is necessary to formulate general rules which work well enough in the majority of cases.
Sooner or later , however , cases arise in which , in some cases, unforeseen sets of facts , the general rules produce substantial unfairness.
When this occurs , justice requires either an amendment of the rule or , if the rule is not freely changeable , a further rule or body of rules to mitigate the severity of the rules of law.
This new body of rules or equity is therefore distinguishable from the general body of law, not because it seeks a different end , for both aim at justice , nor because it relates necessarily to a different subject matter, but because it appears at a later stage of legal development.
Although in many cases equity intervened to put right an injustice, it must be thought that injustice was the subject of equitable intervention. – Snell