 In addition to being expressed by the competent organ of the state, consent to be bound by a treaty must be genuine and informed. Therefore, the Vienna Convention establishes that consent can be invalidated if it results from an error, this is Article 48, from a fraud, Article 49, from the corruption of the representative of the state concerned, Article 50, or from coercion exercised on the representative of the state, Article 51, or coercion exercised on the state itself, Article 52. I'm not going to dwell upon the issues of error, fraud, corruption and coercion on the representative of the state. Those issues are indeed clearly regulated by the Vienna Convention, they are not conceptually difficult to grasp, and moreover there is very little, if not no practice in that regard. And this is because states will always be hesitant to confess that they concluded a treaty by error, by fraud, corruption, etc. Alleging any of those grounds is confessing some form of weakness, something that states do not like to do. This being said, Article 52, which is coercion on the state itself, Article 52 deserves a few words of explanation because it reflects, in the law of treaties, the logical consequences stemming from the outlawory of war. The provision reads as follows and I quote, a treaty is void if its conclusion has been procured by the threat or use of force in violation of the principles of international law embodied in the Charter of the United Nations, end of quote. First, the way Article 52 is drafted deserves some explanation. It does not refer to the threat or use of force in violation of the Charter of the UN, but in violation of the principles of international law embodied in the Charter. In 1969, this was to accommodate the presence of parties to the Vienna Convention that were not yet members of the United Nations. But this clearly indicates that the Charter rules on the threat or use of force are customary rules binding on all states. Those rules are called principles to stress their importance. Second, it is important to consider the nature of the force whose threat or use may entail the invalidity of the treaty. Article 52 simply refers to the threat or use of force without any other qualification. Does that mean that not only military force, but also economic or political coercion are grounds to invalidate treaties? Well, the issue was hotly debated during the negotiation of the Vienna Convention. The negotiators being divided between the western powers that only accepted that military coercion could result in the invalidity of a treaty, and the case at point being the ultimatum imposed by the Nazi government on Czechoslovakia in 1938 by which the Sudetenland was annexed by Germany following the Munich Agreement between the western states on the one hand and the newly decolonized and developing states that wanted to be able to protect themselves against economic and political coercion. The compromise that was found in Vienna was to limit coercion as a ground for invalidating treaties to military coercion under Article 52, because the UN Charter only prohibits the threat or use of military force. While at the same time making clear in a declaration which is part of the final act of the Vienna Convention, making clear that economic and political coercion are also solemnly condemned and that in the future no pressure should be exerted in any form by any state in connection with the conclusion of a treaty. In other words, economic and political pressures should not be resorted to. However, despite being condemned, those pressures are not grounds for invalidating a treaty. Well, this being said, one should not be too naive about it and one should not think that states always refrain from exerting any form of pressure in order to help concluding the conclusion of treaties. Of course they do and this is what diplomacy is largely about. However, the most egregious forms of economic or political pressure could be considered as possible grounds for international responsibility which is something different from putting into question the validity of the treaty resulting from it. Lastly, it is important to note that it is not any threat or any use of armed force which is ground for treaty invalidity. Indeed, it is only if the threat or use of force is, I quote again, in violation of the principles of international law embodied in the Charter of the United Nations, that the treaty resulting from it is invalid. Well, concretely, this means that a peace treaty imposed by the aggressor state would be invalid whereas a peace treaty imposed by the victim state acting in self-defense would be perfectly valid. In other words, not every military coercion is illegal and not every treaty imposed as a result of the use of force is invalid. And this is perfectly logic and reasonable. From the moment international law prohibits wars of aggression, as we shall see later in the lectures, treaties resulting from such wars cannot be considered as being validly concluded. Any other solution would turn the prohibition on the use of force on its head. At the same time, a rule in validating treaties that have been imposed as a result of a lawful use of force would be totally counterproductive. Indeed, it would practically mean that a lawful belligerent would never be entitled to put an end to the war it won by a legal instrument. And this would be an absurd result.