Subject to the provisions of this Constitution, the executive power of a State shall extend to the matters with respect to which the Legislature of the State has power to make laws:
Provided that in any matter with respect to which the Legislature of a State and Parliament have power to make laws, the executive power of the State shall be subject to, and limited by, the executive power expressly conferred by this Constitution or by any law made by Parliament upon the Union or authorities thereof.
Article 162 of the Constitution lays down the extent of executive power of the State. Executive power is the authority to govern the State and to enforce orders.
The 7th Schedule of the Constitution of India gives the allocation of powers and functions between the Union (Centre) and the States. It consists of three lists - Union List, State List and the Concurrent List. The Union Government/Parliament has the exclusive power to legislate on matters relating to items in the Union List. Similarly, the respective State Governments have exclusive power to legislate on matters/subjects given in the State List. Under the IIIrd List, i.e. the Concurrent List, both the Union and the State authorities have jurisdiction to legislate.
According to this Article, the State's executive authority is exclusive for those matters that are mentioned in List II (State List) of the Seventh Schedule of the Constitution of India. This authority also extends to the IIIrd List i.e. the Concurrent List, except if the Constitution or any law that may have been passed by the Parliament say otherwise.
This Article does not specify the definition of what executive power or function is, but is only concerned with the area of or distribution of the executive powers of the State. Article 162 states that the powers of the State executive extend to those matters upon which the State has the power or the authority to legislate/make laws, and are thereby not confined to those matters over which the States have already legislated upon. Similarly, Article 73 of the Constitution lays down the extent of executive power of the Union.
If any law that has been enacted by the Parliament lays down that the Union authorities have the power or duty to execute a certain law on a subject in the Concurrent List, then, the State would not be left with the power to exercise executive functions in relation to that subject (up to the extent of powers exercisable by the Union authorities).
Any decision in exercise of the executive power of the Government can be reviewed by the Court under Article 226 of the Constitution. The judiciary's powers are limited to examining whether the Government acted in a bona fide manner and on relevant considerations only.
According to the wordings of Article 162, the extent of executive power of a State is coextensive with its legislative power. In the Concurrent List i.e. the IIIrd List, the executive power of the State would be subject to any laws conferring power to execute on the Union. Where the powers of executing a law on a subject mentioned in the Concurrent List are conferred upon the Union Authorities/Government, by any law enacted by the Parliament or by the Constitution, the executive powers of the State to that extent would stand abrogated.