An eternity clause in the constitution or basic law of a country is designed to ensure that the law or constitution cannot be changed by amendment. Eternity clauses are a type of entrenched clause that exist in the constitutions of the Czech Republic, Germany, Turkey, Greece, Italy, Morocco, the Islamic Republic of Iran, the Federative Republic of Brazil and Norway.
The German eternity clause (Ewigkeitsklausel) is Article 79 paragraph (3) of the Basic Law (Grundgesetz-GG) for the Federal Republic of Germany. The eternity clause establishes that certain fundamental principles of Germany's democracy can never be changed, even by parliament. The fundamental principles, (i.e., "the basic principles" of Articles 1 and 20), are as follows:
- Duty of all state authority: "The dignity of man is inviolable. To respect and protect it is the duty of all state authority." Art. 1;
- Acknowledgement of human rights: "The German people therefore acknowledge inviolable and inalienable human rights as the basis of every community, of peace and of justice in the world." Art. 1 Para. (2);
- Directly enforceable law: "The following basic rights bind the legislature, the executive and judiciary as directly enforceable law." Art. 1 Para. (3);
- Republic (form of government): Art. 20 Para. (1);
- Federal state (Länder): Art. 20 Para. (1);
- Social state (welfare state): Art. 20 Para. (1);
- Sovereignty of the People: "All state authority emanates from the People." Art. 20 Para. (2);
- Democratic: "All state authority is exercised by the people by means of elections and voting and by specific legislative, executive and judicial organs." Art. 20 Para. (2);
- Rule of law (Rechtsstaat): "Legislation is subject to the constitutional order. The executive and judiciary are bound by the law." Art. 20 Para. (3);
- Separation of powers: "Specific legislative, executive and judicial organs," each "bound by the law." Art. 20 Paras. (2) and (3).
The Parlamentarischer Rat (Parliamentary Council) included the eternity clause in its Basic Law specifically to prevent a new "legal" pathway to a dictatorship as was the case in the Weimar Republic with the Enabling Act of 1933.
It is not possible for any political party, any legislation or any national commitment to violate "the basic principles" of "this Basic Law" laid down in Articles 1 and 20. Furthermore, the only way that Articles 1 and 20 can be amended is through Article 146 which requires "a constitution that is adopted by a free decision of the German People."
Unlike the Weimar Constitution, which made human rights only an objective, the eternity clause and Articles 1 and 20 make specific demands of "all state authority" regarding "human rights" (that is, "the basic rights" guaranteed in "this Basic Law") and have established specific legislative, executive and judicial organs in "the constitutional order" of "this Basic Law", each with separate functions bound by the law. These are "the basic principles" of the democratic rule of law (Rechtsstaat) and the separation of powers, which are principles endorsed by three United Nations resolutions.
The final Article of the Constitution of the Islamic Republic of Iran, Art. 177, ensures that particular aspects of the Constitution are unalterable. These include the Islamic character of government and laws, the objectives of the republic, the democratic character of the government, “the absolute wilayat al-'amr and the leadership of the Ummah”, the administration of the country by referendum, and the official religion of Islam.
In the Constitution of Morocco, eternity clauses exist that ensure certain provisions cannot be amended, including the role of Islam in the nation's law, and the role of the King of Morocco in law.
Article 60 paragraph 4th of the Constitution of the Federative Republic of Brazil, lists four subject areas of the Constitution that cannot be amended: i) format of the federation; ii) direct, secret universal and periodic voting; iii) separation of powers; and iv) individual rights and guarantees. 
- Kyriaki Topidi and Alexander H.E. Morawa (2010). Constitutional Evolution in Central and Eastern Europe (Studies in Modern Law and Policy). p. 105. ISBN 978-1409403272.
- Joel Colón-Ríos (2012). Weak Constitutionalism: Democratic Legitimacy and the Question of Constituent Power (Routledge Research in Constitutional Law. p. 67. ISBN 978-0415671903.
- Gerhard Robbers (2006). Encyclopedia of World Constitutions. p. 626. ISBN 978-0816060788.
- "Defending German Democracy". National Review. 2 July 2012.
- "The Euro Crisis: Challenges to the ESM Treaty and the Fiscal Compact Treaty before the German Constitutional Court". Institute of International and European Affairs. 30 August 2012.
- "United Nations and the Rule of Law". Un.org.
- http://www.iranchamber.com/government/laws/constitution_ch13.php The Constitution of the Islamic Republic of Iran