As outlined in the document itself, here are two ways to amend the Constitution.
One is to hold a constitutional convention, which must be proposed by two-thirds of the state legislatures.
That has never happened.
The other is to have two-thirds of both houses of Congress — the House of Representatives and the Senate — approve a proposed amendment. Ratification then requires the approval of legislatures in three-fourths of the states.
Thousands of amendments have been proposed since the Bill of Rights. Congress has approved 33 amendments over the years; only 27 have been ratified by the states.
Among the proposed amendments that were approved by Congress but failed to win ratification by the states was the Equal Rights Amendment (ERA), which, according to the national Council of Women's Organizations, "would provide a fundamental legal remedy against sex discrimination for both women and men."
Mary Frances Berry, a proponent of the ERA, is the Geraldine R. Segal Professor of American Social Thought at the University of Pennsylvania and a former chair of the United States Commission on Civil Rights.
In a 1987, she wrote a piece for the New York Times about the failure of the ERA to gain ratification. In discussing the inherent challenge of amending the Constitution, Berry observed:
"The makers of the Constitution wanted to create a firm basis for the exercise of governmental power. However, they were wise enough to know that if they made their document too rigid, if they wrote it so that it could not be revised to suit future times and events, they were inviting future revolution. They would be creating a situation in which the only method to effect change would be to cast aside the Constitution itself. As George Mason noted at the 1787 convention, changes would be necessary, and it would be 'better to provide for them in an easy, regular and constitutional way than to trust to chance and violence.'
"So they made it open to change — but not open to change without great effort. James Madison was among those who warned against making things too easy. It was important, he said, to guard 'against that extreme facility which would render the Constitution too mutable.' For if it could be altered easily, the Constitution would be mere temporary law, not a document for the ages."
Because of that, Berry explained, "Change requires two elements: consensus and necessity. There must be substantive national agreement, as well as agreement in most of the states, that an urgent problem exists that cannot be remedied by the courts, legislatures or Congress, and which can be solved only if the Constitution is changed." —Curt Guyette