Brazil is, without a doubt, an energy giant. By virtue of its natural, environmental and climatic conditions, the country has different energy matrices, both renewable and nonrenewable. These include hydro energy, thermal energy, wind energy, fossil-fuel-derived energy and bioenergy. The energy sources available and explored in Brazil are diverse. This exploration cannot occur outside the law. Judicial guidelines are the instrument used by the State to allow rational exploration of different energy sources in order to cater to public and private interests linked to such exploration. It is no wonder that fossil fuels, particularly oil, natural gas and their derivatives, are widely studied energy sources regulated by judicial guidelines. Whether because of their economic and political importance or their nonrenewable nature, Brazilian law seeks to regulate the exploration and production of these energy sources as a way of safeguarding the collective interest and making exploration and production as efficient as possible. At the same time, the environmental variable is also a constant concern for the Brazilian legal order, especially due to the potential polluting level of fossil fuels. On the other hand, ever since the oil crises of the 1970s, the Brazilian State has been concerned with developing biofuels, a second important renewable energy matrix, through the “National Alcohol Program” (“PROALCOOL”), encouraging the production of biofuels, which are still widely consumed today in the form of alcohol. The advent of this second energy source catalyzed all the development of the biofuel industry in the contemporary energy scenario, with special emphasis on biodiesel. This brings us to the purpose of this book. Notwithstanding the title (Energy Law in Brazil), the work we present here is underpinned by the study of Brazilian judicial guidelines that regulate the oil, natural gas and biofuel energy sectors.