The Amendment process is the formal way to change the Constitution. An amendment may be proposed by two-thirds vote of both houses of Congress or by a convention called by Congress at the request of...
There are two entities that can amend the Constitution: Constitutional Amendments are typically a joint venture between Congress and the states. Either the House of Representatives or the Senate may...
WHenever two thirds of both houses of congress think it's neccesary. Or a national convention called by congress at the request of two thirds of the state legislators.