I guess you could say that a constitution is a lot like a project charter. One of the most important elements to the success of any kaizen event for example, is a well-defined charter. It aligns everyone's thoughts and actions to solving the problems at hand and delivering the expected results. It's open enough to allow for creativity and adaptation, but it also sets basic ground rules by which to act. Without it, even the most concerted effort can easily spiral into confusion and disagreement.
Consider our own constitution for example. The preamble has many of the basic elements of a good kaizen charter:
We the People of the United States (establish the team), in Order to form a more perfect Union (continuous improvement toward an ideal state), establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity (scope, problem statement, and deliverables), do ordain and establish this Constitution for the United States of America.
It then goes on to spell out the structure and tools to be used for one of the most audacious and most successful (so far) continuous improvement efforts of all time: The United States of America.