Articles 12–13

Article 12 — "the State": Whenever Part III says "the State shall not...", we need to know who "the State" is. Article 12 defines it broadly to include: the Union Government and Parliament; the State Governments and State Legislatures; all local authorities (municipalities, panchayats, district boards); and "other authorities" within India or under the control of the Government of India. That last phrase — "other authorities" — has been the site of enormous litigation, because it decides whether a statutory corporation, a university, or a body like ONGC or LIC counts as "State" and can therefore be sued for violating a Fundamental Right. In Rajasthan State Electricity Board v. Mohan Lal (1967) and later Ajay Hasia v. Khalid Mujib (1981), the Supreme Court laid down functional tests — deep and pervasive government control, government funding, monopoly status, and functions of public importance — to decide if a body is an "instrumentality or agency of the State" and thus bound by Part III even though it isn't literally a government department.

Article 13 — the "guardian clause": Article 13(1) says all laws in force before the Constitution commenced, to the extent they are inconsistent with Part III, are void. Article 13(2) forbids the State from making any new law that takes away or abridges Fundamental Rights, and any law made in contravention is void to that extent. Two doctrines flow from this:

• Doctrine of Severability: only the offending part of a law is struck down, not the whole statute, provided the valid part can stand independently.
• Doctrine of Eclipse: a pre-Constitution law inconsistent with a Fundamental Right isn't wiped out — it becomes dormant ("eclipsed") and springs back to life if the relevant Fundamental Right is later amended so that the inconsistency disappears. This doctrine, crucially, applies only to citizens challenging a law and only to pre-existing laws — a post-Constitution law void under Article 13(2) is void ab initio for everyone, and there's no "eclipse" to lift.

Article 13(3) clarifies that "law" here includes ordinances, orders, bye-laws, rules, regulations, notifications, and even custom or usage having the force of law — but, importantly, the Supreme Court in Shankari Prasad v. Union of India (1951) initially held that a constitutional amendment under Article 368 is not "law" within the meaning of Article 13, so amendments could not be struck down for violating Part III. This position later became the central battleground of the FR–DPSP conflict (see below), reversing in Golaknath (1967) and finally settling into the Basic Structure compromise of Kesavananda Bharati (1973).