Indonesia holds one of the world's largest tropical forest reserves, yet persistent deforestation continues to threaten the constitutional guarantee of a good and healthy environment enshrined in Article 28H(1) and the state's mandate to manage natural resources for public welfare under Article 33(3) of the 1945 Constitution. While prior studies have examined the constitutional right to environment in general terms, this study offers novelty by using the December 2025 flash flood disaster in Sumatra, which killed hundreds and displaced thousands, as a concrete case study to empirically test the extent to which these constitutional mandates have been implemented in forest governance. Employing a normative juridical method with a statute approach, this study analyzes national forestry and environmental regulations against the constitutional provisions. The findings show that despite a net national deforestation figure of 175,400 hectares in 2024, law enforcement institutions handled only 187 criminal cases and imposed 3,474 administrative sanctions in the same year, a scale gap that reflects weak institutional oversight rather than a lack of regulatory instruments. The study concludes that fulfilling the constitutional mandate on environmental protection requires strengthening institutional enforcement capacity and integrating ecological indicators into national development planning, rather than relying on normative declarations alone.