Question

why residuary subjects are not included in union list

Answer 1

Because the residuary subjects came much later after independence . Example is information technology. The subjects in the residuary list do not fall in any category. Union government has the power to legislate on these subjects.

Answer 2

Matters which are not included in the division of powers, are known as residuary powers. After the independence and the drafting of constitution, they felt that there might be new subjects coming up in the future. It was felt that there can be subjects which are not mentioned in either of these lists. The central government has been given the power to legislate on these ‘residuary’ subjects.