Soft law plays an important role in the protection and conservation of environment. In particular environmental law has developed soft law instruments like treaties, declarations, general principles like an example sustainable development goals (SDGs), and guide-lines. Indeed non-binding norms define the protection of environment, in particular after Stockholm Conference, through the creation of UNEP and the Johannesburg Declaration on sustainable development. This paper analyzes the evolution that lead soft law to acquire autonomous role in environmental protection. It started to be applied as such and without the neet of a transposition in norms of hard law. Now, instead, soft law creates norms deliberately non-binding that have legal relevance and able to create a “soft obligation”. (In Italy, an example, the numerous cases of guide-lines regarding environment and in partucular waste andling storage and transportation).