aequitas sequitur legem
Equity does not override clear rules of law. It supplements the law where the law is incomplete or harsh, but where a statute or settled rule covers the matter, equity must respect it. Equitable estates were modelled on legal estates for the same reason.
In India, equitable principles are mostly codified in the Specific Relief Act, the Trusts Act and the Transfer of Property Act. The Supreme Court has repeatedly said that equity cannot be used to defeat an express statutory provision, such as a limitation period. Equity acts only in the gap left by law.
Example
The court refused to extend the limitation period on grounds of hardship, because aequitas sequitur legem and the Limitation Act left no room for discretion.
See also
equity · he who seeks equity must do equity · aequitas agit in personam · limitation