This paper develops a theoretical approach to measuring institutional quality in hybrid jurisdictions, understood as legal systems where civil-law codification and commonlaw adjudication coexist in a structurally integrated way. Standard indica-tors of institutional quality È rule of law, judicial efficiency, legal certainty, and enforcement effectiveness ‒ are conceptually tailored to legally homogeneous sys-tems and can generate systematic bias when applied to hybrid orders. Building on institutional economics and measurement theory, the paper models institutional quality as a multidimensional construct driven by inter-source coherence, stability of conflict-resolution rules, and the capacity of the legal order to sustain predicta-ble governance under legal pluralism. The framework clarifies which dimensions are invisible to traditional metrics and provides a principled architecture for hy-brid-specific measurement, enabling meaningful comparison across mixed sys-tems without econometric estimation. It also yields testable qualitative implica-tions for institutional design, reform priorities, and crossjurisdictional benchmark-ing exercises today.