An
amendment is a change to the
constitution of a nation or a state. In jurisdictions with "rigid" or "entrenched" constitutions amendments require a special procedure different from that used for enacting ordinary laws.
A flexible constitution is one that may be amended by a simple act of the legislature, in the same way as it passes ordinary laws. The 'uncodified' constitution of the United Kingdom (UK) consists partly of important statutes, and partly of certain unwritten conventions. The statutes that make up the UK constitution can be amended by a simple act of Parliament. UK constitutional conventions are held to evolve organically over time. The Basic Laws of Israel may be amended by an act of the Knesset.
The constitutions of a great many nations provide that they may be amended by the legislature, but only by a special, extra large majority of votes cast (also known as a supermajority, or a "qualified" or "weighted" majority). This is usually a majority of two-thirds the total number of votes cast. In a bicameral parliament it may be required that a special majority be achieved in both chambers of the legislature. In addition, many constitutions require a that an amendment receive the votes of a minimum absolute number of members, rather than simply the support of those present at a meeting of the legislature which is in quorum. For example, the German 'Basic Law' (the Grundgesetz) may be amended with the consent of a majority of two-thirds in both the Bundestag (lower house) and Bundesrat (upper house). The constitution of Brazil may be amended with the consent of both houses of Congress by a majority of three-fifths. An amendment to the Australian Constitution requires both a majority of the voters nationally and a majority of the voters in a majority of the States i.e. the measure must be carried in four of the six States as well as nationally.
Some constitutions may only be amended with the direct consent of the electorate in a referendum. In some states a decision to submit an amendment to the electorate must first be taken by the legislature. In others a constitutional referendum may be triggered by a citizen's initiative. The constitutions of the Republic of Ireland, Denmark, Japan and Australia are amended by means of a referendum first proposed by parliament. The constitutions of Switzerland and of several United States states may be amended through the process of popular initiative.