In Portugal, creation of legislation is the primary method in which the actual standards of environmental protection that are represented in the constitution are given clarity and substance. In this sense, the legislative branch of government acts as the longa manus of the constitution. The environmental provisions are given clarity as the legislation determines precisely what aspects of the environment are protected and the extent to which that protection is provided; they are also given substance through legal mechanisms that can be used in the event of non-compliance. To examine the development of standards associated with the environmental provisions of the Portuguese constitution, this chapter considers the relationship that they have had on the development of infra-constitutional standards. The standards that correspond with the constitutional provisions are placed into three categories: those areas where the legislation responds directly to the requirements of EU law; those instances where Portuguese standards go further than EU law; and also those standards which do not respond to EU law and can be seen as national autonomous initiatives. It is in the latter two categories in particular that specific standards of environmental protection related to the provisions of the national constitution can be clearly identified.