Despite the existence of multiple laws that codify regulations defining environmental crimes, illegal practices in extractive activities tend to occur because rules are not enforced. This study therefore aims to advance explanations as to why there is low effectiveness of enforcement of regulations to tackle environmental crimes in extractive activities. We draw on the law enforcement literature to identify explanations for why environmental enforcement fails to deter illegal practices in extractive activities. We then take up the case of illegal mining in artisanal and small-scale gold mining (ASGM) in the region of Madre de Dios (MDD) in the Peruvian Amazon. We evaluate qualitative data from multiple sources including legal documents, reports and interviews. The findings suggest two issues that have shaped low enforcement effectiveness in MDD: conflicts and lack of collaboration among agencies at different levels and sectors of government, and inadequate resource allocation from the national government to other levels. Enforcement is not monolithic in one governmental authority; therefore, it is crucial to recognize and address the existence of multiple levels and sectors of enforcement to improve the effectiveness of enforcement actions. These findings bear implications for theoretical perspectives on enforcement as well as public policies to increase effectiveness of enforcement of environmental regulations.