A/HRC/22/43 issues and their relevance to a wide range of actors in the fields of human rights and environmental policymaking. 38. At the same time, the multitude of relevant forums makes the study of human rights obligations pertaining to the environment conceptually challenging. The development of this field has been rapid and widely dispersed, but it has also been highly fragmented. Although the various bodies engaged in the process of developing and implementing a rights-based approach to environmental policy occasionally look to one another for guidance, they often have different sources of authority, different audiences and different mandates. For example, the increasing attention devoted by treaty bodies and special procedures to environmental issues, while highly valuable, is necessarily focused on particular rights or problems. While the opinions of a regional human rights tribunal are of great importance for States within the region, the relevance for countries outside it may be less clear. The use of environmental rights in domestic law varies from State to State and may not always shed light on the scope of the rights at the international level. Moreover, the application of human rights law to environmental issues has often developed on a caseby-case basis. In sum, while there is no shortage of statements on human rights obligations relating to the environment, the statements do not come together on their own to constitute a coherent set of norms. 39. Nevertheless, as the previous chapter also indicates, the human rights and environmental bodies that have examined these issues do seem to have reached some areas of convergence in their approaches. Wherever possible, the independent expert will seek to find such areas with respect to human rights obligations. In that respect, he will be guided by the language of resolution 19/10. By requesting study of the human rights obligations relating to the environment and a compilation of best practices in the use of human rights obligations to improve environmental policymaking, in consultation with interested actors in all areas, the resolution encourages the Independent Expert to examine the use of rightsbased approaches to environmental protection through a wide lens. Human rights obligations relating to the environment may fall along a spectrum, from duties that are generally binding on all States, to those that bind a smaller number of States that have accepted them through regional agreements or that have adopted them in their own constitutions or other laws. Obligations that bind only some States may nevertheless be worthy of consideration by other States as possible best, or good, practices.27 B. Substantive and procedural rights and duties 40. In examining the obligations pertaining to the human rights vulnerable to environmental degradation, perhaps the most basic set of issues concerns the substantive and procedural content of those obligations. One interesting development in this respect concerns possible links between substantive rights and procedural duties. Some human rights bodies have, in effect, closed the circle between the (largely substantive) rights that are most likely to suffer environmental harm, and the (largely procedural) rights whose implementation helps to ensure environmental protection. In order to safeguard the environment from the types of harm that violate the first set of rights, they have concluded that States have obligations to respect and ensure the second set of rights. 27 The Independent Expert agrees with the statement of the then Independent Expert on the issue of human rights obligations related to access to safe drinking water and sanitation that “rarely can a practice be qualified as best and that the concept of good practices is preferable” (A/HRC/10/6, para. 34, footnote 37). 13