 To find out about the practice of states, scholars and sometimes courts, turn to what is called digests of practice, which are reports published by foreign affairs ministries or academics about the various things that the government of one state has done in international relations over a certain period of time. Many western states have been publishing their practice relating to international law in books and periodicals for many years, and more and more states do likewise today. Of course, the more accessible the practice of one state is, the more influential it will be in the formation of custom. It is quite obvious that if the practice of a state is only known to a few of its civil servants, it will not bear much influence on the crystallization of customary rules. Hence, very often, the theoretical question about whose practice will concretely end up as being a question about whose practice is accessible and has been made public, both in a searchable form and in a language which is internationally used. State practice is not only scrutinized by individual scholars. It is also closely studied by two bodies I would like to mention here. Each of them is tasked with the study, codification and progressive development of international law. Taking them in the chronological order, I'll start with the International Law Institute, Institut de droits internationales in French. The Institute is a learned society. It is a private body founded in 1873 and composed of 132 members elected by their peers. The Institute has been very influential in the late 19th century and during a good part of the 20th century and it was awarded the Nobel Peace Prize in 1904. The Institute meets every second year in order to adopt resolutions on various issues of private and public international law. Those resolutions very often codify, write down customary rules and also déléguer de ferrenda suggest some improvements. The other body I would like to mention is the International Law Commission or ILC. The ILC is an official body established by the General Assembly of the United Nations. It is today composed of 34 members. They are elected by the General Assembly upon the suggestion of the various governments and as it is usual at the UN, each region of the world is allocated a certain number of members within the Commission. The members of the ILC sit in their individual capacity, not as national delegates. They are not only international law professors, but they are drawn from the various segments of the international legal community so they may include former diplomats, former state officials or former international civil servants. The International Law Commission, like the Institute, is tasked with the codification and progressive development of international law. It appoints special rapporteurs on certain topics, those rapporteurs write down reports and suggest draft articles which are discussed by the ILC. The interesting part is that unlike the Institute, the ILC interacts with the member states of the UN by putting questions to their governments, collecting their answers and listening to their comments on its work. And the Commission meets every year and its work is later discussed every year also at the Sixth Committee of the General Assembly, which is the legal committee of the United Nations. The end product of the ILC work often serves as a basis for a diplomatic conference that will result in a treaty, like, as we shall see, the Vienna Convention of 1969 on the Law of Treaties, or more recently the 2005 New York Convention on Jurisdictional Immunities of States and Their Property. In other cases, the ILC draft articles are adopted by the UN General Assembly in a resolution and its content will very largely reflect existing customary law. And this is, for instance, the case with the ILC articles on the responsibility of states for internationally wrongful acts that we are going to study. To find out more about the Institute and the ILC, feel free to click on the links that you will find on this page below this video. However, the safest way to identify customary rules is to read case law by international courts and tribunals. After all, as the Latin maxim puts it, yura novit curia, which means the judge knows the law. So if the International Court of Justice considers that such a customary rule exists or does not exist, it is safe to assume that this pronouncement is correct, or rather, from a positivistic point of view, that finding has certainly more weight and more authority than the writings of a scholar. It is interesting to notice that, depending on the content of the rule at stake, the ICC takes more or less pain in giving reasons for the conclusions it reaches as to the existence or non-existence of the said rule. This does not really come as a surprise and should not be the cause for criticism, because simply put, some rules are more obvious than others and raise less political tensions than others.