The present Korean government announces planning to build the Kyongin Canal and to repair the four major rivers that may be connected through construction of waterway. This plan triggers the confrontation of development and environment. Ecosystem protection movement led by the nongovernmental organizations including Korean Federation Environment Movement(KFEM), founded in April 1993 after the UN Conference on Environment and Development(UNCED) in Rio de Janeiro in 1992, collapsed the freshwater lake plan by Sihwa tide embankment and prevented construction of a dam on the Dong river, But the movement to stop the reclamation of the Samangeum wetlands brought environmental issues to the Administrative Court, the Supreme court and the Constitutiual court for judicial judgements. This paper analyzes the Samangeum cases regarding environmental-related issues about right to environment, standing to sue, circumstances change and burden of proof. Right to environment or the definition of environment is not cleariy settled yet because of a wide diversity of opinions from ecosystem to all surroundings of mankind. Right to environment is only constructed through the provisions of the Constitution and laws ; thus, article 35 of the Constitution doesn`t directly provide any specific right to environment, No future generation nor nature itself stands to sue without new enactment. Solution on confrontation of development and environment should depend on monetary values of environment relating economic validity analysis and environmental impact assessment, although what and how to assess environmental values doesn`t unfortunately reach perfect agreements. In my opinion, judicial judgements should be based on comparing monetary values of development and environment among the imperfect or conflict evidences produced on pleading.