“ When proposed in either mode amendments to be effective must be ratified by the Legislatures, or by conventions, in three-fourths of the states, 'as the one or the other mode of ratification may be proposed by the Congress.' Thus the people of the United States, by whom the Constitution was ordained and established, have made it a condition to amending that instrument that the amendment be submitted to representative assemblies in the several states and be ratified in three-fourths of them. ”

“ These were the circumstances in the light of which Congress in proposing the Eighteenth Amendment fixed seven years as the period for ratification. Whether this could be done was questioned at the time and debated at length, but the prevailing view in both houses was that some limitation was intended and that seven years was a reasonable period. [6]
That the Constitution contains no express provision on the subject is not in itself controlling; for with the Constitution, as with a statute or other written instrument, what is reasonably implied is as much a part of it as what is expressed. ”

“ We conclude that the fair inference or implication from article 5 is that the ratification must be within some reasonable time after the proposal.
Of the power of Congress, keeping within reasonable limits, to fix a definite period for the ratification we entertain no doubt. As a rule the Constitution speaks in general terms, leaving Congress to deal with subsidiary matters of detail as the public interests and changing conditions may require ”