Objective understanding of whether a legal instrument is effective involves consideration of the purposes of the instrument and its realworld effects. This is at least partly an empirical enquiry, similar to policy evaluation. It requires factual evidence of outcomes and data to underpin hypotheses about the causes of outcomes. These empirical enquiries must go beyond instrument design and the actions of legal agencies. Practical outcomes will often reflect context issues like social and cultural receptivity to legal arrangements, politics, economic capacity and impacts, and the dynamics of socio-ecological systems. As well, the resources invested to support a legal instrument, and the implementation strategy, are often determinants of success. The question that this raises is whether our legal scholarship is suited to addressing implementation questions beyond doctrinal, procedural and philosophic/jurisprudential concerns. If legal scholarship is indeed concerned with improving the effectiveness of the environmental law system, this suggests the need for methodologies and knowledge that can illuminate the empirical questions: what works, when, and why?