World Constitutions: Written, Unwritten, Rigid, and Flexible

This site's own Salient Features of the Constitution note already covers, in full, the borrowed-features table UPSC tests most often: which specific provision India took from which country's constitution. That table is not repeated here. This chapter's own content is different: standalone facts about other countries' constitutions as they actually function, independent of anything India borrowed from them.

Written versus unwritten: a genuinely small club

A written constitution exists as a single, codified document (or a small set of them). An unwritten (or uncodified) constitution instead draws its authority from statutes, judicial precedent, and long-standing convention, with no single document collecting it all. The United Kingdom, along with New Zealand and Israel, are the only three countries in the world with an uncodified constitution, a genuinely small, specific list worth memorising exactly rather than assuming "several" major democracies share this feature.

Rigid versus flexible: how hard is the constitution to change

A rigid constitution requires a special, more demanding procedure to amend than an ordinary law, typically a supermajority or an additional ratification step. The United States Constitution is the standard example: an amendment ordinarily needs a two-thirds vote in both Houses of Congress, followed by ratification by three-fourths of the states, a genuinely high bar that has produced only 27 amendments since 1787. A flexible constitution, by contrast, can be changed by the same ordinary legislative procedure used for any other law. The United Kingdom's constitution is flexible in exactly this sense: since it is not a single codified document with its own special amendment procedure, an ordinary Act of Parliament can modify or abrogate any constitutional rule or institution.

The oldest written constitution: two different, both correct, claims

This is the chapter's most precise trap. The Constitution of the United States, adopted in 1787, is the oldest still-operative national written constitution in the world. But the Massachusetts Constitution of 1780, drafted principally by John Adams, is older still and remains in force today as the oldest written constitution of any kind, national or sub-national, still in continuous effect. A question asking for "the oldest written constitution in the world" without specifying national-level is testing whether a candidate knows this distinction exists at all, not just the US Constitution's own 1787 date.

Judicial review's actual origin: Marbury v Madison, 1803

Judicial review, the power of a court to strike down a law as unconstitutional, is not named anywhere in the US Constitution's own text. It originates instead in Marbury v Madison (1803), in which the U.S. Supreme Court, in a unanimous opinion by Chief Justice John Marshall, held for the first time that a court could declare an Act of Congress unconstitutional and void. This is worth holding precisely against this site's own Supreme Court note, which already establishes that India's own judicial review rests on several articles read together (13, 32, 226, 245); the American doctrine, by contrast, was never written into that Constitution's text at all, and exists purely because Marbury v Madison established it as a matter of judicial interpretation.

Quick revision points

• Unwritten/uncodified constitutions: only three countries, the United Kingdom, New Zealand, and Israel.
• Rigid: the US Constitution (two-thirds of both Houses of Congress, plus ratification by three-fourths of the states). Flexible: the UK's, changeable by an ordinary Act of Parliament.
• Oldest written constitution: the US Constitution (1787) is the oldest still-operative national one; the Massachusetts Constitution (1780) is older and is the oldest written constitution of any kind still in force.
• Judicial review originates in Marbury v Madison (1803), Chief Justice John Marshall, not from any express textual grant in the US Constitution itself, a contrast worth holding against India's own textually-grounded judicial review.

Holding these as facts about how other constitutions actually work, distinct from the separate borrowed-features table this site's Salient Features note already covers, is what keeps this short chapter from collapsing into a repeat of that other one.