International Environmental Law has no clear boundaries but many grey areas that intersect with other areas of research such as business, ecology, humanitarian and human rights law. Till the beginning of 1970s, majority of international agreements usually aimed at serving the altruistic purposes. Stockholm Conference in 1972, on Human Environment , for the first time pondered upon the need to limit the damages to environment. All the international agreements on Environment were meant to reconcile with the national legislation which thoroughly sought to preserve the environment. All the different types and kinds of pollution including the soil erosion and disposal of dangerous and hazardous waste have awakened the upholders of environmental protection and have spread the awareness of taking up this issue seriously, for prevention is better than any other medicine on earth. In the case of environment, the municipal issues cannot be separated from the global ones. As a result of which the preface of international and domestic environmental law is rapidly expanding. Environmental laws of the particular states are the barometers that administer and manage Natural Resources and Environmental Quality examples of such may be water and air pollution, agricultural methods.
Objective of International Environmental Law
Over population, development of technology and exploitation of resources, world has become a vulnerable place. Globalization of markets and evolution of cohesive civil society has presented new challenges alongside new opportunities. These challenges are the reason that a global law on environment was necessary for the preservation of both natural and man-made resources for future generations. Other areas of international law such as trade, business and human rights are also seeping into environmental law because its niche is trans-boundary.
Economies and Sustainable Development
Economic development has been the goal of world since many years now. Economic expansion is considered fundamental and mandatory to ending poverty in the developing world and raising standards of living worldwide. In the 21st century, the pace with which the economic development is happening, it is in conflict with the environmental sustainability. World however cannot over look development, all it can do is to bring out green development. We cannot subdue development all we can do is to integrate development and environmental protection and bring about sustainable development.
Compliance vs Effectiveness of IEL:
International Environmental Law is a set of treaties and conventions which the states voluntarily comply with. According to the Vienna Convention on the Law of Treaties 1969 (VCLT), there are certain treaties which have binding value. International Law is a way lot different than the municipal law in sense that there is no pet enforcing agency but since we are dealing with states, their independence and sovereignty, so the question of any positivist agency doesn’t even arise.
When dealing with environmental law, the Multilateral Environmental Agreements (MEAs) are the ones whose compliance matters greatly from those of domestic environmental rules and regulations. When we take up the examples of Montreal Protocol on Substances that Deplete the Ozone Layer 1987 and Kyoto Protocol 1997 we come to know that the compliance procedures are attached thereunder. Compliance theories are not made in vacuum; rather these theories are linked with the general principles of International Law. Even those treaties which are non-binding or even non-binding norms have a role in promoting compliance with the obligations undertaken under MEAs.
Enforcement of International Environmental law:
There are forums where international environmental disputes can be adjudicated, such as the International Court of Justice and international arbitration panels, however, international forums unlike national courts do not exercise compulsory jurisdiction. These forums generally require that the disputing parties voluntarily submit to the jurisdiction of the court or panel. The kind of sanctions conceived beneath the Montreal Protocol and International Whaling Commission are extremely hard to inflict. In essence, there isn’t any global structure licensed/allowed to promptly implement the international environmental law. The job of prompt implication remains with states, whose governmental authorities suggest and take up the task of getting the policies implemented. Sometimes the implementing national legislation is identical to the international agreement. For example, Canada implemented the Migratory Birds Treaty (with the United States) by adopting the Migratory Birds Treaty Act. Because the language of this act is identical to language in the treaty, the law is basically a legislative codification of the international agreement. 
National Environmental law:
It is the constitutional right of every citizen of the state to have access to safe and clean environment and the right to life. In Pakistan, there was Pakistan Environmental Protection Act framed in 1997 which after the 18th Amendment to the Constitution became Provincial Environmental Protection Act because the subject of environment had been delegated to the provinces. As a result of 18th Amendment, Punjab Environmental Protection Act 2012 came into force. The main purpose of PEPA is the protection and preservation of environment and to save the depletion of resources.
Environmental Law in Pakistan:
The development in Pakistan related to the arena of environment has been progressing ever since the national legislation on environment has been passed. To regulate the environmental concerns which were increasing day by day due to the developmental factor, certain rules and regulations have been formulated. Thus keeping in view the environmental concerns of this particular territory we established the specific regulatory authorities and particular agencies to regularize the environmental concerns on the particular methods of regularizing environment. We have progressed a lot since 1996 and have a lot to look forward to in the coming years primarily because of the fact that the field of environment has boomed in the past 2 decades and the scope of environment has increased due to the boom in development and technology.
Main Purpose of Punjab Environmental Protection Agency:
National Environmental Protection Agencies were formed throughout the world as the result of 1972 conference in Stockholm or 1992 conference in Rio. However, it is mainly the international agreements in compliance of which the national environmental strategy and enforcement systems are formed. It is the goal of almost all the nations to shift to green economy, poverty eradication and to develop sustainably. Multidisciplinary approaches to capacity building for parliamentarians, inspectors, prosecutors, and judges are keys to this process.
The main purpose of Punjab-EPA is to enforce the environmental law and to develop rules and regulations for its enforcement, apart from approving the Environmental Impact Assessment (EIA), and Initial Environmental Examinations. It is mandated to prepare and establish the Provincial Environmental Quality Standards with the approval of the Punjab Environmental Protection Council and to take measures to promote research and development of science and technology which may help in the protection and prevention of pollution. The Agency may undertake inquiries or investigation into environmental issues, either of its own accord or upon complaint from any person or organization.
Goal of Sustainable Development:
The idea of sustainable development is vague and primarily because of this reason it has gained worldwide support and universal acceptance among every strata of society. Development in every society is measured by the amount of satisfaction with which peoples’ needs are being fulfilled. In a world where people’s basic needs are not being met, that world will always be prone to environmental crisis. Sustainable development is the development that meets the needs of present generations without compromising the ability of future generations to meet their own needs; in other words it requires meeting the basic/essential needs of all and extending to all the opportunity to satisfy their aspirations for better life.
Article 9 and Environmental Law:
The Stockholm Conference (United Nations Conference on the Human Environment, 1972) was the first large meeting organized by the United Nations focusing on environmental issues. The meeting was convened as a result of growing international concern for the preservation of nature and of the dissatisfaction among various sectors of society with regard to the impact of pollution on the quality of life. Article 9 of the Constitution of Pakistan deals with the right to life and implies that it is the right of every citizen of the state to have an access to safe, healthy and clean environment in addition to the obligation to protect environment. This article imposes an obligation for the Public authorities to preserve and defend the environment for the present and future generations.
Thus to protect the interests of present and future generations, it is the inherent duty of the state to protect and preserve its land and environment by proportional usage of its resources. The main goal of international and national legislation on environment is to minimize the adverse impacts of development on the quality of air, water and other natural elements so as to sustain the overall integrity of ecosystem.
 International Environmental Law and policy by David Hunter, Salzman and Zaelke
 What is International Environmental law? Global Change Instruction Program