This chapter looks at the link between environmental disputes, movements, and defenders and the use of the law to target environmental defenders. It explains and clarifies how environmental conflict and ‘defenders’ are conceived and employed throughout the book. The chapter introduces the conceptual framework – hegemonic environmental lawfare (HEL) – used throughout the book to examine attacks against environmental defenders through legal means. Furthermore, the chapter elaborates on the strategic dimensions of HEL: geographies, weaponry, externalities, and resistance. It argues that HEL in Southeast Asia should be placed in a wider structural context by scrutinising the functions of law and legal institutions in capitalist development in the region. It is argued that HEL is a response and reaction to the question of legitimacy in relation to the political and economic status quo.