<P> After being officially proposed, either by Congress or a national convention of the states, a constitutional amendment must then be ratified by three - fourths of the states . Congress is authorized to choose whether a proposed amendment is sent to the state legislatures or to state ratifying conventions for ratification . Amendments ratified by the states under either procedure are indistinguishable and have equal force as part of the Constitution . Of the 33 amendments submitted to the states for ratification, the state convention method has been used for only one, the Twenty - first Amendment, which became part of the Constitution in 1933 . This was also one of only four times that Congress has placed the mode of ratification in the body of an amendment rather than in accompanying legislation; the others being the Eighteenth, Twentieth, and Twenty - second Amendments . In United States v. Sprague (1931), the Supreme Court affirmed the authority of Congress to decide how each individual constitutional amendment is ratified, in accordance with the options provided in Article V and the equal validity of amendments properly ratified in either fashion . The Court had earlier, in Hawke v. Smith (1920), ruled the ratification of the proposed Nineteenth Amendment (which Congress had sent to the state legislatures for ratification) by the Legislature of Ohio could not be referred to the electors (voters) of the state, and that the Ohio Constitution, in requiring such a referendum, was inconsistent with the U.S. Constitution . </P> <P> An amendment becomes an operative part of the Constitution when it is ratified by the necessary number of states, rather than on the later date when its ratification is certified . No further action by Congress or anyone is required . On three occasions, Congress has, after being informed that an amendment has reached the ratification threshold, adopted a resolution declaring the process successfully completed . Such actions, while perhaps important for political reasons, are, constitutionally speaking, unnecessary . </P> <P> Presently, the Archivist of the United States is charged with responsibility for administering the ratification process under the provisions of 1 U.S. Code § 106b . The Archivist officially notifies the states, by a registered letter to each state's Governor, that an amendment has been proposed . Each Governor then formally submits the amendment to their state's legislature (or ratifying convention). When a state ratifies a proposed amendment, it sends the Archivist an original or certified copy of the state's action . Upon receiving the necessary number of state ratifications, it is the duty of the Archivist to issue a certificate proclaiming a particular amendment duly ratified and part of the Constitution . The amendment and its certificate of ratification are then published in the Federal Register and United States Statutes at Large . This serves as official notice to Congress and to the nation that the ratification process has been successfully completed . </P> <P> The Constitution is silent on the issue of whether or not Congress may limit the length of time that the states have to ratify constitutional amendments sent for their consideration . It is also silent on the issue of whether or not Congress, once it has sent an amendment that includes a ratification deadline to the states for their consideration, can extend that deadline . </P>

When can voting on a constitutional amendment happen