Unwritten Constitutional Modification
It is so difficult to amend the Constitution, we mostly don't do it. Our system is to have the Supreme Court migrate slowly through several small adjustments, watching the country respond. Occasionally we have imported new principles, sometimes not entirely wise ones, adopted without the same seasoning.
Westphalia: Church Politics Adjusts Boundaries, Then Everything Changes
In 1648, the Treaty of Westphalia created the modern nation-state.