This chapter considers activism in the context of struggles for social and ecological justice. It outlines a radical perspective on eco-justice –namely, a critical green criminology. Resisting crimes of ecocide is motivated by the need to respond to a singularly important trend: the existing planetary environment is rapidly being destroyed. Expansion of specialist environment courts and tribunals as well as development of a wide range of sanctions and remedies is also important areas for further agitation in pursuit of robust responses to environmental crimes. A distinctive critical green criminology perspective consists of three broad approaches, focusing respectively on political economy, ecology and species justice. A distinguishing characteristic of critical green criminology is that it generally takes an oppositional stance in relation to much of the work of conventional criminology, and also many contemporary policy developments in the field of criminal justice.