The Constitution provides that an amendment may be proposed either by the Congress with a two-thirds majority vote in both the House of Representatives and the Senate or by a constitutional convention called for by two-thirds of the State legislatures.
An amendment may be proposed by a two-thirds vote of both Houses of Congress, or, if two-thirds of the States request one, by a convention called for that purpose. The amendment must then be ratified by three-fourths of the State legislatures, or three-fourths of conventions called in each State for ratification.
The amendment process is very difficult and time consuming: A proposed amendment must be passed by two-thirds of both houses of Congress, then ratified by the legislatures of three-fourths of the states.
Second, compared to other ways of changing laws, it is very difficult to amend the Constitution. For an amendment to be approved, two-thirds of both houses of Congress must pass the amendment. (An amendment can also pass with a two-thirds vote at a national convention, but this has never happened before).
The amendment must then be ratified by three-fourths of the State legislatures, or three-fourths of conventions called in each State for ratification. In modern times, amendments have traditionally specified a time frame in which this must be accomplished, usually a period of several years.
Congress must call a convention for proposing amendments upon application of the legislatures of two-thirds of the states (i.e., 34 of 50 states). Amendments proposed by Congress or convention become valid only when ratified by the legislatures of, or conventions in, three-fourths of the states (i.e., 38 of 50 states).
14 The easiest constitution to amend, by his calculation, was the Constitution of New Zealand, which is amendable by a simple legislative majority in the country's unicameral legislature.
An amendment of the Constitution can be initiated only by the introduction of a Bill in either House of Parliament. The Bill must then be passed in each House by a majority of the total membership of that House and by a majority of not less than two-thirds of the members of that House present and voting.