It is often said that Brazil has some of the most advanced forest laws in the world, but this strong legislation has been rarely translated into effective environmental governance. To understand the challenges of implementing environmental policies in Brazil and elsewhere, this study conceptualizes the Forest Code as a socially constructed technology, the effects of which emerge from its specific uses. We find that, in contrast to the prevailing view of this law as having no effects in practice, it produced multiple and contradictory impacts due to its appropriation by different social groups. For the technocrats, the law was a partial success as it represented progress towards science-based territorial planning. For the Rural elite the Forest Code was used as way to block access of poor settlers to fertile public areas to preserve future elite agricultural expansion. Finally, settlers viewed the Code as a way to obtain official clearing authorizations used to substantiate future titling claims. From this examination, the article argues that the prevailing economic and legalist perspectives on the effectiveness of environmental policies need to be complemented by sociological perspectives in order to account for the nondeterministic character of scientific perspectives, laws and the social dynamics behind the multiple appropriations of state apparatuses. By understanding how laws, as technologies, are interpreted and appropriated by different social actors we will be able to contribute by proposing legal apparatuses that are more appropriate for the local context in which they are supposed to function. Apropriaçoẽs, conflitos e subversoẽs do Código Florestal Brasileiro Costuma-se dizer que o Brasil possui algumas das leis florestais mais avançadas do mundo, mas essa forte legislação raramente se traduz em uma governança ambiental eficaz. Para entender os desafios na implementação de politicas ambientais no Brasil e em outros KEYWORDS Socio-environmental conflicts; Brazil; Forest Code; social construction of technology; law as technology PALAVRAS-CHAVE Conflitos socio-ambientais; Brasil; Código Florestal; construção social da tecnologia; lei como tecnologia PALABRAS CLAVE Conflictos socio-ambientales; Brasil; Código Forestal; construcción social de la tecnología; ley como tecnología