What is legislative power?

Legislative power means the power of the Law-making organ of the State to make ordinary laws or statutes to regulate the conduct of the citizens towards each other and towards the State. 

Since the Legislature, which makes such laws, is a creature of the Constitution, it cannot amend the Constitution itself in exercise of its power to make ordinary laws, because of the general doctrine of ultra vires

In India, the legislative power of the Union is vested in the Parliament, and that of a State is vested in a State Legislature and the distribution of this power between Parliament and the State Legislatures is effected by Articles 245-250 of the Constitution.

The Union Parliament can make laws in exercise of the aforesaid legislative power if it complies with the ‘legislative procedure’ laid down in Articles 107-117, but cannot amend any provision of the Constitution in accordance with that procedure.

 What is Constituent power?

Constituent power means the power to make or change the Constitution by which the various organs of the State, including the Legislature itself, are created. 

Unless, therefore, the constituent power is limited by any express limitation, the constituent body, complying with the prescribed procedure, may amend any part of the Constitution, without being confronted by the doctrine of ultra vires. 

To distinguish between the legislative and constituent power, one must remember the distinction between ‘ordinary law’ and ‘constitutional law’. 

An ordinary law is made by the legislature set up by the Constitution of a State. Constitutional Law is the law arising out of that Constitution which sets up the different organs of the State, including the Legislature itself. Legislative power is the power in exercise of which the Legislature makes ordinary laws; constituent power is the power in the exercise of which the Constitution itself is made, unmade or altered.