The Constitution would also likely defend your personal agency in a civil trial
(ex. 'freedom of speech'; Bill of Rights).
I see your point concerning natural rights, while there is an ideological value to codifying principles within the public arena where individuals interact.
My subsequent critique of the Constitution otherwise is that it has not explicitly defined those principles which shall not be violated
-currency (inc. monetary specie)
-corporality (one’s body)
-sovereignty (freedom to travel)
-philosophy (ex. free speech)
-spirituality (ex. freedom of religion)
and its ethic regarding coercion has been inconsistent
(ex. instituting taxation)