Defensor Santiago vehemently opposed mining. She believes mining is one of the greatest reasons why local communities are impoverished as most of the profit coming from mining are siphoned by mining companies away from the local economy. In addition, mining has made numerous destructive advances in Philippine society and ecosystems, destroying watersheds and agricultural lands, as well as rivers and seas. According to an interview conducted by Haribon Foundation during the 2016 Presidential Campaign, the organization voted her as the "greenest" in all of the candidates. She was the main author of the Climate Change Law and the Renewable Energies Law in the Senate.