By retracing the evolution of the Lacey Act, I intend to examine the mechanics of overcriminalization and the growth of federal criminal law. Initially passed as a narrow statute designed to address illegal wildlife poaching in a way that respected the concepts of federalism, the Lacey Act has transformed into a broad and sweeping federal law that can be used to target individuals and businesses that are not even aware they are engaging in criminal conduct. Some changes to the Lacey Act have contributed to this problem more significantly than others, and a specific understanding of how and why these changes were made may be able to prevent future laws from transforming in a similar fashion. By delineating the way in which the discrete components of this law have developed, this case study can help legislators and policymakers recognize what to avoid when drafting and amending statutes—and the repercussions of failing to do so. As the Lacey Act’s history so vividly illustrates, powerful interest groups may nonetheless win out in their efforts to transform laws in accor- dance with their interests. But those looking to push back against this pressure will be more successful if armed with a proper understanding of how overcriminalization can occur and what policies are best suited to prevent its proliferation.