Which constitutional provision allows Parliament to legislate on a State List matter when two or more States request Parliament to do so?

Article 252 provides a unique mechanism of cooperative federalism, allowing Parliament to legislate on State List subjects if two or more States consent. Such laws apply only to consenting States unless others adopt them later. This provision balances State autonomy with national coordination, enabling uniform regulation where States perceive collective benefit. Examples include laws on wildlife and water management. Courts have upheld Article 252 legislation as constitutionally valid, emphasizing that State consent preserves federal principles while enabling legislative flexibility.