The diversion of water from the Meuse Case Netherlands v Belgium

The Netherlands claimed that Belgium had infringed a treaty obligation by building canals that altered the flow of water in the River Meuse. Belgium responded that Netherlands had lost the right to bring a claim because of similar earlier conduct on its part

The court recognition of equity as part of IL is in no way restricted by a special power conferred upon it ‘to decide a case ex aequo et bono’. Under art 38, if not independently of it, the court has some freedom to consider principles of equity as part of IL which it must apply. An important principle of equity is ‘he who seeks equity must do equity’ where two parties have assumed an identical or reciprocal obligation, one party which is engaged in a continuing non performance of that obligation should not be permitted to take advantage of a similar non performance of that obligation by the other party.