 Catherine, thank you very much and let me start by really thanking the organisers who've done such a fantastic job organising this webinar. This is great to be able to engage with the fellow speakers and with the audience as well. So today I'd like to say a few words on the principle of prevention in international environmental law with a specific focus on the geographical scope of a preventive obligation. As we know international environmental law is based on the willingness to avoid environmental harm before it happens based on the idea that we should avoid harm from occurring rather than repairing the damage. So it is generally acknowledged that this preventive principle is customary international law having found its origins in the landmark award of a trail smelter case and then having consolidated in the form of principle 21 of a Stockholm declaration. For the purposes of this presentation the three fundamental components of a principle of prevention as expressed in principle 21 are quite important. As we know the first component is one that says that states have sovereign rights to exploit their own natural resources. So very much a principle focus on the sovereignty of the state when it comes to its environment within its domestic territory and then to more environment focused components with a traditional prohibition to cause transboundary harm to other states and an even more environment friendly component about protecting the environments in the global comments. What we are seeing really is that even in this principle of prevention sovereignty preservation remain central. So we have on the one hand the sovereignty of a state to exploit its resources that is balanced with the sovereignty of other states to be and their right to be free from external interferences. However if we look at the landmark advisory opinion on environment and human rights of the inter-american court of human rights from 2017 what we see here is that the advisory opinion says that states have a duty to prevent damage to the environments and they quote both inside and outside their territory. So this affirmation actually raises questions about the geographical scope of a preventive duty as we are indeed going beyond the transboundary context in which principle 21 has operated so far. So what I'd like to do today is to assess whether and if so under which circumstances states might have a duty to prevent harm to the environment within the jurisdiction or control even when no external impact can be reasonably foreseen. So I will start with some brief preliminary methodological remarks. I will then very briefly outline a number of either environmental or human rights obligations that might be applicable in a purely domestic context and then I will explain why does this matter why does this matter that we have actually an obligation that state might have an obligation to prevent harm only within the domestic territory. So understandably the thesis of the extension of a spatial scope of prevention is not uncontroversial it is challenging with a traditional conception of prevention as a norm designed to preserve the territorial integrity of states and while there's a lot of doctrinal discussions about the fact that the concept of sovereignty might be might be reshaped by a globalized world we see that the proposition by a state can use its resources at its feet is rarely actually open and challenged. However at the same time if we look at some codification works from the UN environment program from the IUCN environment and development covenants as well as some of the legal scholarship for instance if you look at the textbook of sands and peel we see here that there's often an illusion to the applicability of prevention in a purely domestic context. So what I'd like to do today is to look under which circumstances can we say that such an obligation can apply. This is raising a fundamental question that relates to whether a norm exists in customer international law and if so how do we actually go about in trying to identify such the existence of such a customary norm. So I do not seek to undertake a comprehensive assessment of state practice or opinionaries but what I'd like to do today is to highlight a number of obligations that are actually asking states already to preserve their environment within their domestic territory. So if we look at international environmental obligations what we see is that sovereignty again remains quite important and this is those obligations are very much driven by a willingness to preserve sovereignty and not the environment as such. However we can identify three sets of obligations that creates a domestic obligation to prevent harm. The first one is if we transpose the international norm harm rule to a domestic setting in a situation where an administrative entity in a state such as a province or canton or land causes environmental harm to the territory of another domestic administrative entity within that same state. So this is what we have seen in relation to a number of decisions from domestic courts in which domestic courts have actually applied the international norm harm rule looking for instance at a 12 melting case or the ILC prevention articles in a purely domestic setting. So they've used this norm harm rule as an inspiration to actually regulate and try to protect the environment within their own territory. Such transposition obviously has its own limits it works better if we are in a federal system it might not work all the time because it's not really creating an overall obligation to avoid harm within the territory of a state. A second possibility is to look at the emerging obligations of sustainable use of natural resources that has been considered to be an emerging norm on the customer international law by the international law association for instance. Again here we are only looking at how states are using their resources within their domestic territory and we are in a sense including this preventive rationale in that obligation but preventive rationale that has nevertheless to be balanced with the other components of sustainability economic and social consideration. So it means that the preventive obligation does not have that will not prevail over necessarily over other considerations. And then the third component and the one that is perhaps more convincing is relates to the general duties to protect the environment that we see in certain international treaties in article 192 of the UN Convention of the Law of a Sea that creates a broad obligation to prevent to preserve the environment irrespective of where harm might happen which means that it also includes the domestic territory of a state. Same thing with the UN International Watercourse Treaty or even the work that is being done by the ILC on the protection of the atmosphere where we can also find that kind of broad environmental obligation. The second approach is to look also at human rights duties but in a sense are better suited when we're trying to identify state obligations in the context of a purely domestic activities. And in this context we can look at the obligation to prevent and mitigate disasters to protect people as has been identified in the work of International Law Commission. An obligation that has actually that finds its background in the environmental principle of prevention but that has been applied only in a pure domestic context irrespective of external impacts. The two obligations are obviously linked but they are also very different as when we're talking about disasters we are talking about an emergency, a focus on protecting the population and not the environment as such. And then a second type of obligations that relates to the increasingly important case law that we have on relationship between human rights and the environment. Here again an implicit obligation to prevent harm in as much as certain activities might affect the enjoyment of existing human rights. This jurisprudence is often implicit when it comes to recognizing this obligation of prevention but for instance if we look at the latest judgment of the Inter-American Court of Human Rights from February 2020 in La Cajon against Argentina what we see in this judgment is that there is a specific reference based on the advisory opinion that I mentioned previously about the preventive duty to avoid environmental damage and about how this preventive duty applies in a strictly domestic context. So why does this matter? Well it matters because basically if we're only looking at principle 21 as an expression of the prevention principle well we actually see that this is not enough and that there are there might be some emerging duties to protect the environment also within a state's domestic territory. This kind of objective standing in which prevention applies irrespective of where environmental harm might happen has consequences both legal and symbolic. Legally speaking if we have a territorial norm of prevention it means that states will have an obligation to avoid environmental damage in disputed areas and this is what has been recognized by the International Tribunal on the Law of the Sea in Ghana, the Sous-Portivoire or in the South China Sea arbitration points. So this is quite important because it means that we have obligations that are applicable irrespective of sovereignty considerations. In addition and perhaps more controversially it also means that we could perhaps justify a right to take unilateral preventive measures which allows the objective of environmental protection to actually prevail over the right of a state to be free from external interferences. Theoretically speaking the objective standing is significant because it's really signaling a change in the logic that drives international law in the context of environmental protection. It is making prevention applicable irrespective of sovereignty considerations and hence better able to value the environment per se. Thank you.