This chapter focuses specifically on one legal response to dealing with conserving species, namely regulating the international trade in endangered species in the face of illegal international trade in wild animal species, and the devastating effects of this on biological diversity. Examples are given of the current situation in Southeast Asia. The chapter considers (in fact, re-examines) the Convention on International Trade in Endangered Species of Wild Fauna and Flora 1973 (CITES) and its implementation, with particular focus on Southeast Asia and its regional centre for combating wildlife trade, the ASEAN Wildlife Enforcement Network (ASEAN-WEN). Examples are given of successes and failures. Recognition of illegal wildlife trade as a transnational environmental crime is called for and there is examination of the UN Convention against Transnational Organized Crime 2003 (UNTOC); the UN Convention against Corruption 2003 (UNCAC); the ASEAN Mutual Legal Assistance Treaty on Criminal Matters 2004 (MLAT); International Standards on Combating Money Laundering and the Financing of Terrorism and Proliferation 2012 (FATF); and the London Declaration on Wildlife Trade 2014. The chapter finally canvasses various possible solutions, and makes recommendations for more effective policing and enforcement in the context of ASEAN and East Asia.