2. Rivers which traverse two or more states.
3. Rivers upon the opposite banks of which different states have jurisdiction.
(a) Rivers which traverse only one state are exclusively within the jurisdiction of that state. This jurisdiction may extend even to the forbidding of the use of a river to other states, and justifies the state in prescribing such regulations for its use as it may deem fit.
(b) Rivers flowing through two or more states are for those parts within the boundaries of each state under its jurisdiction for the purposes of police, tolls, and general regulations. The right of absolute exclusion of the co-riparian states by any one of the states through which a river flows has been the subject of much discussion, and authorities of great weight can be found upon either side.
(c) When two states have jurisdiction upon opposite banks of a river, the jurisdiction of each state extends to the middle of the main channel or thalweg. Before the Treaty of Luneville (Art. VI.), 1801, it had been common to consider the limit of jurisdiction of the two states the middle of the river, a line much more difficult to determine, and more changeable than the channel line. The thalweg has been frequently confirmed as the accepted boundary where no conventions to the contrary existed.[135]
[§ 51. The Navigation of Rivers]
The laws of jurisdiction of rivers are generally accepted. The early idea that there was a natural right of navigation, and innocent passage has received less support during the nineteenth century than formerly. The history of river navigation during the nineteenth century, as shown in the discussions between the representatives of various nations, and in the treaties and conventions agreed upon, as well as in treaties and declarations voluntarily made in regard to navigation of rivers, seem to furnish general rules.
1. That international law gives to other states no right of navigation of rivers wholly within the jurisdiction of another state.
2. That when a river forms the boundary of two or more states it is open to the navigation of each of the states.
3. That when a river passes through two or more states, international law gives no right to one of the states to pass through the part of the river in the other state or states. There is a strong moral obligation resting upon the states below to allow freedom of navigation through the river to the states upon the upper course of the river. The right of innocent use, innocent passage, freedom of river navigation, has been maintained on various grounds and in various forms, by many authorities.[136] Those who take a position opposed to this claim, assert that the navigation of rivers is, and properly should be, to avoid more serious complications, a matter of convention.