Past legal language exerts an almost magnetic force on negotiators. From boilerplate treaties or copy-and-paste adaptations to the codification of prior jurisprudence – practitioners constantly recycle already existent terms, phrases, and concepts into new legal outputs. This chapter links the reproduction of legal language to the concept of path-dependency and applies it to international investment agreements. The chapter shows that historical sociology rather than rational design helps to explain the path-dependent style and content of today’s investment regime. Using the fair and equitable treatment clause as a case study, the chapter traces how these clauses first emerged haphazardly in investment law, yet then became entrenched through efficiency considerations, sociological forces, and cognitive biases. The ensuing path-dependency has prevented adaptations of superior treaty design alternatives, and instead geared negotiators into reproducing or refining the fair and equitable treatment standard. Differently put, negotiators have become locked in language. The chapter concludes by outlining ways in which current reform efforts can overcome the system’s path-dependency to allow for innovation inspired not by past practices but by current needs.