The thematic analysed is the evolution of the Precautionary Principle. It is a valuable tool for developing adequate decisions in situations where there is large uncertainty . The situations of uncertainty can be of different types and different entities. Indeed, the precautionary principle éncourages policies that protect human health and the environment in the face of uncertain risks. In recent years, legislators’ attention has focused increasingly on actions to protect the environment and the human health. On the international plane, nations have accepted the precautionary principle as a basis for their policies. For these motivations, the analysis of the PRECAUTIONARY PRINCIPLE appears an interesting thematic to study: indeed, it is important to understand if the principle could be an opportunity to improve and protect our world or a bureaucratic quibble.