A constitutional amendment is a formal change to the text of the written constitution of a nation or state. In some jurisdictions the text of the constitution itself is altered; in others the text is not changed, but the amendments change its effect.
Most constitutions require that amendments cannot be enacted unless they have passed a special procedure that is more stringent than that required of ordinary legislation. Examples of such special procedures include super-majorities in the legislature, or direct approval by the electorate in a referendum, or even a combination of two or more different special procedures. A referendum to amend the constitution may also be triggered in some jurisdictions by popular initiative.
Australia and the Republic of Ireland provide examples of constitutions requiring that all amendments are first passed by the legislature before being submitted to the people; in the case of Ireland, a simple majority of those voting at the electorate is all that is required, whereas a more complex set of criteria must be met in Australia (a majority of voters in a majority of states is also necessary). Switzerland has a similar procedure to Australia's.
Denmark provides an example of multiple special procedures that must be followed. After an amendment has been approved by parliament, a general election must be held; the new parliament must then approve the amendment again before it is finally submitted to a referendum. There is also a requirement that at least 40% of eligible voters must vote at the referendum in order for an amendment to be validly passed.
The special procedures for the amendment of some constitutions have proven to be so exacting that of proposed amendments either few, as in Australia, or none, as in Japan, have been passed over a period of several decades. In contrast, the constitution of the US state of Alabama has been amended over 800 times since 1901.
Form of changes to the text 
There are a number of formal differences, from one jurisdiction to another, in the manner in which constitutional amendments are both originally drafted and written down once they become law. In some jurisdictions, such as the Republic of Ireland, Estonia and Australia, constitutional amendments originate as bills and become laws in the form of acts of parliament. This may be the case notwithstanding the fact that a special procedure is required to bring an amendment into force. Thus, for example, in the Republic of Ireland and Australia although amendments are drafted in the form of Acts of Parliament they cannot become law until they have been approved in a referendum. By contrast, in the United States a proposed amendment originates as a special joint resolution of Congress that is not submitted to the President for his or her assent.
The manner in which constitutional amendments are finally recorded takes two main forms. In most jurisdictions, amendments to a constitution take the form of revisions to the previous text. Thus, once an amendment has become law, portions of the original text may be deleted or new articles may be inserted among existing ones. The second, less common method, is for amendments to be appended to the end of the main text in the form of special articles of amendment, leaving the body of the original text intact. Although the wording of the original text is not altered, the doctrine of implied repeal applies. In other words, in the event of conflict, an article of amendment will usually take precedence over the provisions of the original text, or of an earlier amendment. Nonetheless, there may still be ambiguity whether an amendment is intended to supersede or to supplement an existing article in the text.
An article of amendment may, however, explicitly express itself as having the effect of repealing a specific existing article. The use of appended articles of amendment is most famous as a feature of the United States Constitution, but it is also the method of amendment in a number of other jurisdictions, such as Venezuela.
The Constitution of Austria is unusually liberal regarding the recording of constitutional amendments. Any piece of parliamentary legislation can be designated as "constitutional law", i.e. as a part of the constitution if the required supermajority and other formalities for an amendment are met. An amendment may take the form of a change of the Bundes-Verfassungsgesetz, the centerpiece of the constitution, a change to another constitutional act, a new constitutional act, or of a section of constitutional law in a non-constitutional act. Furthermore, international treaties can be enacted as constitutional law, as happened in the case of the European Convention of Human Rights. Over the decades, frequent amendments and, in some cases, the intention to immunize pieces of legislation from judicial review, have led to much "constitutional garbage" consisting of hundreds of constitutional provisions spread all over the legal system. This has led to calls for reform.
Under the 1919 German Weimar Constitution, the prevailing legal theory was that any law reaching the necessary supermajorities in both chambers of parliament was free to deviate from the terms of the constitution, without itself becoming part of the constitution. This very wide conception of "amendment" eased the rise of Adolf Hitler to power; it was consequently explicitly ruled out in the postwar 1949 constitution[clarification needed], which allows amendments only by explicitly changing the constitution's text.
Inadmissible amendments 
Some constitutions use entrenched clauses to restrict the kind of amendment to which they may be subject. This is usually to protect characteristics of the state considered sacrosanct, such as the democratic form of government or the protection of fundamental human rights. Amendments are often totally forbidden during a state of emergency or martial law.
- Under Article 79 (3) of the German Basic Law, modification of the federal nature of the country or abolition or alteration of Article 1 (human dignity, human rights, immediate applicability of fundamental rights as law) or Article 20 (democracy, republicanism, rule of law, social nature of the state) is forbidden. This is supposed to prevent a recurrence of events like those during the Nazi Gleichschaltung, when Hitler used formally legal constitutional law to de facto abolish the constitution.
- The final article of the Constitution of Italy (Article 139, Section 2, Title 6 of Part 2) holds the "form of Republic" above amendment.
- Article 4 of Part 1 of the Constitution of Turkey states that the "... provision of Article 1 of the Constitution establishing the form of the state as a Republic, the provisions in Article 2 on the characteristics of the Republic, and the provision of Article 3 shall not be amended, nor shall their amendment be proposed."
- Article Five of the United States Constitution, ratified in 1788, prohibited any amendments before 1808 which would affect the foreign slave trade, the tax on the slave trade, or the direct taxation provisions of the constitution. The foreign slave trade was outlawed by an act of Congress rather than by a constitutional amendment shortly after that clause expired in 1808. Also, no amendment may affect the equal representation of states in the Senate without their own consent. If the Corwin amendment had passed, any future amendment to the United States Constitution "interfering with the domestic institutions of the state" (i.e. slavery) would have been banned.
- Chapter 6, Article 120, section c of the Constitution of Bahrain prohibits "...an amendment to Article 2 [State Religion, Shari'a, Official Language] of this Constitution, and it is not permissible under any circumstances to propose the amendment of the constitutional monarchy and the principle of inherited rule in Bahrain, as well as the bicameral system and the principles of freedom and equality established in this Constitution."
- Article 112 of the Constitution of Norway provides that amendments must not "contradict the principles embodied in this Constitution, but solely relate to modifications of particular provisions which do not alter the spirit of the Constitution".
- Section 284 of Article 18 of the Alabama State Constitution states that legislative representation is based on population, and any amendments are precluded from changing that.
- The Constitution of Portugal (Part 4, Section 1, Article 288) contains a long list (15 items) of things which amendments "must respect". It should be noted though that Article 288 itself can be amended.
- The Supreme Court of India in the Kesavananda Bharati case held that no constitutional amendment can destroy the basic structure of the Indian constitution.
- Article 60 of the current 1988 Constitution of Brazil forbids amendments that intend to abolish individual rights or to alter the fundamental framework of the State—the Separation of Powers and the Federal Republic.
- Article 152 of the Constitution of Romania ("Limits of revision") prohibits amendments regarding the independence and territorial integrity of Romania, the independence of justice, the republican form of government, political pluralism and the official language. It also forbids amendments which restrict civil rights and liberties.
See also 
- 2008 Amendments to the Constitution of Russia
- Amend (motion)
- Amendments to the Constitution of Canada
- Amendment of the Constitution of India
- Amendments to the Constitution of Ireland
- Amendments to the United States Constitution
- Constitutional referendums in Australia
- List of methods of constitutional amendment
- List of national constitutions
- List of proposed amendments to the United States Constitution
- "Amendment", by Peter Suber. From Philosophy of Law: An Encyclopedia, edited by Christopher Berry Gray, Garland Pub. Co., 1999, vol. I, pp. 31–32.Bill West 1985- 2003. Vol 98-85-96-6 Law .edu.216 Esd
- The Paradox of Self-Amendment: A Study of Logic, Law, Omnipotence, and Change, by Peter Suber. Full-text of the book, now out of print. Peter Lang Publishing, 1990. For an essay-length synopsis, see "The Paradox of Self-Amendment in American Constitutional Law", Stanford Literature Review, 7, 1–2 (Spring–Fall 1990) 53–78.
- "Population Changes and Constitutional Amendments: Federalism versus Democracy", by Peter Suber. University of Michigan Journal of Law Reform, 20, 2 (Winter 1987) 409–490.
- "Unamendments", by Jason Mazzone, Iowa Law Review, Vol. 90, p. 1747–1855, 2005.