The Constitution of India is federal in character because:

Another related concept is the doctrine of division of powers between the federal or centre and states or provinces. Federal government has law making powers different than that of states or provinces. For example, the subject matters on national defense and foreign affairs often fall with the federal government, and matters of prisons and direct taxes may fall with the state or provincial governments. The doctrine of division of powers stipulates and delimits subject matters or items on which the federal government and provincial/state governments have powers to make laws. The scheme may also involve common items on which both governments may have powers to make laws. Courts have judicial review powers to declare any law as unconstitutional if it is enacted by breaching the demarcation.