Under Doctrine of Harmonization, Supreme court ruled that the Fundamental rights and Directive Principles are in fact supplementary to each other and together constitute an integrated scheme.

Doctrine of Pith and Substance is a doctrine evolved by British Common Law system as a guide to interpret laws apparently in conflict in federal systems having two legislative bodies. The utility of doctrine is that it is useful in determining the validity of the law enacted by the Parliament (Federal Legislature) and Legislative Assembly (Assembly) on the basis of competence to enact law. 

Doctrine of Colorable Legislation like any other constitutional law doctrine is a tool devised and applied by the Supreme Court of India to interpret various Constitutional Provisions. It is a guiding principle of immense utility while construing provisions relating to legislative competence.