How did statutes and substatutes work together in imperial Chinese law?

In imperial Chinese law, the legal system maintained a balance between stability and dynamism through the interaction of statutes (lu) and substatutes (li).

While the core of the imperial code remained remarkably consistent over centuries—with many provisions persisting from the Tang dynasty through the Qing dynasty—the law was not static. Statutes provided the foundational framework for governance, organized into chapters corresponding to state ministries. To address changing circumstances and specific legal needs, these statutes were supplemented by substatutes (li).

A critical feature of this relationship was that substatutes took priority over statutes whenever the two types of measures conflicted. This hierarchical arrangement allowed the state to maintain the legitimating power of the traditional code while simultaneously providing the flexibility necessary to adapt to evolving social and administrative requirements.1