Parliament has the power to make law in the Union List and the states in the state list. Either parliament or the states should not trench upon each other’s field of legislation. If Parliament makes law in state list, it would be ultra vires. This is done by applying the doctrine of pith and substances. The court considers the true nature and character of the legislation.
Case- Prafulla Kumar V/s Bank of Commerce
Bengal money lenders act was passed to protect agriculturist. It was challenged on the ground that it affected promissory note. Money lending is in the state list, the promissory note is a central subject. Hence, the question was whether the state law was invading central subject.
Applying pith and substance, the court held that true character was money- lending and promissory note was incidentally affected. hence, the law was valid.
Case- Gujarat University v/s Srikrishna(1963)
State list: education
Union list: standards in institutions for higher education.
The Gujarat state prescribed Gujarati and Hindi as a medium of instruction under Education. The was challenged as violative of union list.
The true essence was higher education and hence, the state law was held ultra- vires.