The Environmental Impact Assessments (EIAs) have improved in theory and exercise over the years. Nevertheless, there are several flaws which prevent EIA from becoming a useful instrument for promoting Ecosystem-based Management (EBM). For instance, Deep Sea Mining (DSM) operations are expected to create considerable environmental degradation undermining the poorly recognised mechanisms that remain mostly unknown. Evaluating the environmental consequences of DSM operations at all phases of the mining process from exploration to future exploitation has been among the top priorities of the International Seabed Authority (ISA). Hence, this study attempts to define the legal structure of the ISA to assess the environmental consequences of multiple stages of mining. Based on the observation, the existing methods do not reflect a comprehensive EIA process adhering to EBM. Therefore, it can be concluded that deficient impact analyses and inadequate Environmental Impact Statements (EISs) may be accommodated in the absence of a consistent and well-regulated procedure, allowing for double standards or unequal treatment of contractors and potential applicants.