Asif Mahmood

In my previous column, I discussed why it is geographically inaccurate to describe India as the upper riparian state for every river. In the case of several major rivers, India itself is a middle riparian state when viewed in relation to China. But even if, for the sake of argument, we assume that India is the upper riparian state on a particular river, does that fact alone give it the right to stop the flow of water to the downstream state? In other words, does India’s position as an upper riparian state make it the owner of the water that flows through its territory into Pakistan? Does an upper riparian state own the water that passes through its borders?

The answer is: No.

Until the end of the nineteenth century, there was no universally accepted answer to the question of who had the primary right over the waters of a river flowing through several countries. Some states argued that the country through which the river first passed was its rightful owner. This line of thinking gave rise in 1895 to what later became known as the Harmon Doctrine.

The doctrine emerged during the dispute between the United States and Mexico over the Rio Grande. At the time, U.S. Attorney General Judson Harmon argued that because the river first flowed through American territory, the United States enjoyed absolute sovereignty over the waters within its borders, and Mexico had no legal claim over them.

The doctrine reflected the prevailing American outlook of the time. A country that had rarely shown much restraint in exploiting the resources of others was hardly inclined to concede limits over its own. International law, however, never accepted this proposition. The reason was straightforward. If every upper riparian state were allowed to withhold water from downstream countries at will, no international river in the world would remain free from conflict.

The doctrine was so deeply flawed that, over time, even the United States quietly abandoned it in practice. Today, America’s water-sharing agreements with its neighbours are based on the very principles the Harmon Doctrine rejected. The United States now accepts that an upper riparian state is not the owner of the water flowing through its territory.

So when India argues that, as an upper riparian state, it has absolute authority to stop the flow of water, it is effectively relying on a doctrine that international law has never recognised and that has long since been discarded.

In 1966, the International Law Association adopted the Helsinki Rules. Although they were not legally binding in the same way as an international treaty, they marked the first comprehensive effort by leading jurists to establish that international rivers are not the property of any one state. Instead, every riparian state has the right to make equitable and reasonable use of their waters.

An important distinction must be understood here.

The Helsinki Rules did not call for equal distribution. They called for equitable distribution. The difference between the two is fundamental.

If three countries lie along the same river, international law does not require each to receive one-third of its waters. Instead, it considers a range of factors, including population, agricultural needs, historical use, the availability of alternative water resources, climatic conditions, the degree to which the economy depends on the river, and environmental considerations. It is only after weighing all these factors that a fair allocation can be determined.

That is why international water law is not a law of arithmetic. It is a law of justice.

After nearly three decades of sustained legal work, the United Nations adopted the Convention on the Law of the Non-Navigational Uses of International Watercourses in 1997. Today, it is regarded as the foundational instrument of modern international water law.

The Convention rests on two principles that now serve as the guiding framework for almost every major international water dispute.

The first is that every riparian state has the right to equitable and reasonable utilisation of shared water resources.

The second is that no state should cause significant harm to another.

These two principles are inseparable.

If an upper riparian state were granted an unrestricted right to use the water without any obligation to avoid harming downstream states, those downstream countries would remain permanently vulnerable. Conversely, if the obligation to avoid harm completely restricted the upper state’s ability to utilise the river, its own development would be unfairly constrained. International law therefore seeks to strike a careful balance between the two.

The Convention also embodies another important principle: prior notification and cooperation.

Under this principle, if a state intends to build a dam, canal, or any other water project that may affect another riparian state, it must notify the affected state in advance, provide the necessary technical information, and consult on the likely consequences.

An interesting and revealing example is India’s own position regarding China’s projects on the upper reaches of the Brahmaputra. Whenever Beijing has announced major hydropower developments, New Delhi has consistently demanded that China share hydrological data, disclose details of the projects, and avoid actions that could alter the river’s natural flow.

In other words, India asks China to respect precisely the same rights that it seeks to dilute when dealing with Pakistan.

Another objection is often raised.

India argues that it never ratified the 1997 United Nations Convention and is therefore not bound by it. This is an unconvincing argument because international law is not created by treaties alone. A substantial part of it consists of customary international law, which does not depend on a state’s ratification. Once a principle becomes part of customary international law, compliance is expected from all states.

That is why many of the world’s leading international law scholars agree that principles such as equitable and reasonable utilisation, the obligation to avoid significant harm, prior notification, and cooperation are no longer merely treaty provisions. They have evolved into rules of customary international law.

For the same reason, the International Court of Justice has repeatedly relied on these principles in its judgments, regardless of whether the states concerned are parties to a particular treaty.