Tourism represents a large percentage of the GDP in many Pacific nations. Sustainable tourism has received significant coverage in the literature and the natural environment present great potential for tourism, with nature-based tourism a focus for growth, in Melanesian countries. A large number of species (flora and fauna) are affected by key threats, thereby, impacting biodiversity in the region. Both tourism and climate change can exacerbate these threats further. This can be partly dealt with through government policy. This paper aims to explore the constitutions of the Melanesian nations for the ability to facilitate sustainability and sustainable tourism through a content analysis. It was found that three Melanesian nations have a clause relating to the protection of the environment, creating a significant opportunity for these nations to promote sustainable tourism. Nevertheless, policy implementation is limited and the strength of government institutions in relation to the environment needs to be enhanced.