Who has the power to legislate on subjects not mentioned in any of the three Lists?

The correct option is The Union Legislature only..

Explanation

The Constitution of India distributes legislative powers between the Centre and the States via the Seventh Schedule. Subjects that are not enumerated in the Union List, State List, or Concurrent List are referred to as Residuary Subjects.

Constitutional Analysis:

• Article 248: The Constitution explicitly vests the Residuary Powers of legislation in the Parliament. It states that Parliament has the exclusive power to make any law with respect to any matter not enumerated in the Concurrent List or State List.
• Entry 97 of the Union List: This provision is reiterated in the Union List (List I), where Entry 97 assigns "Any other matter not enumerated in List II or List III including any tax not mentioned in either of those Lists" to the Union Legislature.
• Federal Structure: By vesting residuary powers in the Centre, the Indian Constitution follows the Canadian precedent, distinguishing it from the American and Australian systems where residuary powers lie with the States.

Key Takeaway: Under Article 248 and Entry 97 of the Union List, the power to legislate on residuary subjects rests exclusively with the Union Parliament.