Lake Lanoux Arbitration (Countries may act in defiance of International law)

Lake Lanou is high in the Pyrenees Mountains. It is entirely in France, but it drains into the River Carol, which then runs into Spain, and is used for irrigation on its way to the Mediterranean Sea. 19th century treaties between France and Spain established their mutual borders. Those treaties said if one country wanted to interfere with shared waterways in a way that would affect the other, they would negotiate. In 1917, France began considering a dam on Lake Lanou for hydroelectricity. Decades later, in the mid-1950s, they settled on a plan which would divert water from the Carol, but then replace it with water from another river, so Spain would not actually lose any water flows. Spain objected, and the two countries negotiated for years, but eventually France just proceeded on the basis that they didn't actually need Spain's agreement because they weren't reducing the overall flow to the Carol River. Spain took the matter to arbitration. The tribunal found that in any such situation, regardless of treaties, countries sharing a waterway would have obligations to one another. It said, according to the rules of good faith, the upstream state is under the obligation to take into consideration the various interests involved, to seek to give them every satisfaction compatible with the pursuit of its own interests, and to show that in this regard it is genuinely concerned to reconcile the interests of the other riparian state with its own. However, almost in passing, the tribunal made another extremely important statement, noting that in international law there was nothing to stop a country from taking a dominant position in relation to another country, even if it seemed like they were going to use that position to injure their neighbour. The tribunal said, we do not find in international common law any rule that forbids one state acting to safeguard its legitimate interests to put itself in a situation which would in fact permit it, in violation of its international pledges, seriously to injure a neighbouring state. Such actions might harm relations between countries, but sovereign nations can't actually be prevented from behaving badly. From this case we learn that nations sharing watercourses are obliged by good faith to consider each other's interests, and that nations may, if they choose, use their sovereign powers even in ways which seem to threaten harm to their neighbours.