Constitutional Amendment Processes: Formal and Informal Change

The U.S. Constitution is one of the most difficult to amend among democratic constitutions, requiring either a two-thirds vote of both chambers of Congress or a constitutional convention called by two-thirds of state legislatures, followed by ratification by three-fourths of states. Only 27 amendments have been ratified since 1789, with the last substantive amendment (the 26th, lowering the voting age) ratified in 1971.

Germany's Basic Law can be amended by a two-thirds vote of both the Bundestag and Bundesrat, a process that is demanding but more achievable than the American model. However, Article 79(3) contains an 'eternity clause' that prohibits amendments altering the federal structure, human dignity provisions, or the democratic and social character of the state. Canada's constitution requires varying levels of federal and provincial consent depending on the subject matter, with the most important provisions requiring unanimous provincial agreement.

Australia requires both a national majority and majorities in at least four of six states in a referendum, making it one of the hardest constitutions to change in practice—only 8 of 44 proposed amendments have passed since 1901. South Africa's constitution can be amended by a two-thirds vote of the National Assembly and at least six of nine provinces in the National Council, and has been amended 18 times since 1996.