The world’s oldest written constitution still in effect has many inspiring lines, but perhaps the one that most stirs the souls of the patriotic appears in Article 30. Delineating a familiar separation of powers, that Article forbids the legislative, executive, and judicial branches from swapping or mixing functions. “[T]o that end”—and here’s the line—“it may be a government of laws and not of men.” John Adams, the author of that line and most of the rest of the Constitution of the Commonwealth of Massachusetts, penned those words in 1779, eight years before the adoption of the second oldest written constitution still in effect. Writing just over twenty years later, the great Chief Justice John Marshall would affirm, in Marbury v. Madison,...