Definition
Ratification is the formal act of approval that turns a proposed constitutional text into binding law. A document drafted by a convention or amendment proposed by Congress has no force until it is ratified.
For the original Constitution, ratification meant approval by state conventions. For amendments, it means approval by the required number of states. In each case ratification is the moment of consent.
Why it matters
How it works
The original Constitution provided that it would take effect once nine of the thirteen states ratified it, deliberately bypassing the unanimity that had paralyzed the earlier Articles of Confederation. States debated and approved it through specially elected conventions.
For amendments, Article V requires ratification by three-fourths of the states, acting through their legislatures or through conventions, as Congress directs. Only when that threshold is reached does the new text become part of the Constitution.