Using an original dataset of institutional features of 43 colonial charters and constitutions, and a combination of IRT and text based methods, we develop a series of systematic statistical tests to show that early American fundamental laws are best described by a single latent dimension. Changes in those documents reflect the protection and enumeration of rights—something claimed by the revolutionaries themselves. Other factors such as culture, geography or constitutional clauses on other branches do not appear to be nearly as important. An analysis of change shows a dramatic and rapid shift in documents at the time of the revolution (and not with the drafting of the U.S. Constitution in 1787). The results demonstrate a shift in fundamental law that came concurrent with the American Revolution and seems closely tied to the rights provisions introduced into the new American Constitutions. This shift is of incredible importance because it was the moment that vague, non-written aspirations were turned into written protections of the people’s rights—a pattern that would play out over the next few centuries as future constitutions followed this precedent of written constitutions as repositories of rights.