Who has described the Directive Principles and The Fundamental Rights as the…

Concept: A constitution's moral core is the part that states the values by which every act of the State is to be judged, as distinct from the parts that set up the machinery of government. In the Indian Constitution that moral core is carried by two Parts read together: Part III, which guarantees justiciable Fundamental Rights, and Part IV, which lays down the non-justiciable Directive Principles of State Policy.

A descriptive label of this kind belongs to whoever first used it in an authoritative published study or in the framing debates, so an attribution question is settled by locating the phrase in its source text rather than by guessing which famous name fits.

Application: The phrase ‘conscience of the Constitution’ comes from Granville Austin, the American political scientist and constitutional historian. In The Indian Constitution: Cornerstone of a Nation (1966) — the first full archival history of the Constituent Assembly — Austin treats Part III and Part IV as one linked scheme and writes that the Fundamental Rights and the Directive Principles together are ‘the conscience of the Constitution’. He pairs the phrase with his other well-known description of the same two Parts as ‘the core of the commitment to the social revolution’.

Standard Indian polity texts, including M. Laxmikanth's Indian Polity, reproduce the phrase with this attribution.

Cross-check: The three Constituent Assembly figures offered here are each remembered for a different, well-documented contribution:

• Dr. B. R. Ambedkar — Chairman of the Drafting Committee and independent India’s first Law Minister; in the Assembly debates he described Article 32, the right to constitutional remedies, as the heart and soul of the Constitution.

• Alladi Krishnaswamy Iyer — Advocate-General of Madras and a member of the Drafting Committee; his interventions shaped the Assembly’s decision to adopt ‘procedure established by law’ in Article 21 instead of an American-style ‘due process of law’ clause.

• K. M. Munshi — a lawyer and Drafting Committee member who also sat on the Advisory Committee on Fundamental Rights and circulated his own draft constitution to the Assembly.

Because the phrase is a scholarly formulation by Granville Austin rather than any of these framers’ Assembly formulations, the description of the Fundamental Rights and the Directive Principles as the ‘Conscience of the Constitution’ is credited to him.