The law of the sea is a great laboratory for observing the fabric of international law through the interactions between a variety of judicial bodies with jurisdiction to interpret and apply the same legal rules and principles. At first, the plurality of judicial fora available under UNCLOS has created concerns of fragmentation and of competition and forum shopping. These have proved so far unwarranted, since the tribunals generally deliver a uniform interpretation of the applicable law or tend at least toward harmonization. Tribunals have aimed to achieve clarity and consistency of the case law as well as transparency and predictability of the delimitation process. The concept of acquis judiciaire has been used to designate this mechanism of gradual building of a uniform law through the reiteration and cross-referral to existing judicial decisions. It is both a concept and a regulatory tool. It underlies a wilful search of harmonization and shows that judges are essential actors for ensuring the coherence of the international legal system.