In N.K. Jemisin’s Broken Earth trilogy, core laws are written on stone. But the tablets are incomplete, open to interpretation and their authorship uncertain. Nonetheless, Stone Law forms the basis of the governance system. Ultimately, the narrative reveals that the Stone Laws are recent in origin and an instrument of subjugation whose claims to common sense belie its harms. This article considers immutability in law and the ways in which particular laws become as if written in stone. Constitutional law and jus cogens are two examples of immutable worldbuilding laws represented as inevitable, absolute, unyielding and perpetual. Debates in law and humanities on genre, performance, interpretation and the concerns of a particular era are often reflected and refracted through both the laws and the literature of an era. In particular, the practice of worldbuilding is used to demonstrate the wariness necessary when laws are represented as immutable.