The Registrar is responsible for all legal and administrative work, for the assessment and collection of contributions, and for the administration of the accounts and finances of the Tribunal. The Registrar is the regular channel of communications to and from the Tribunal, keeps the List of cases, and keeps copies of communications and agreements as required by the Rules.
The Registrar is assisted by the Deputy Registrar, who acts as Registrar in the absence of the Registrar.
The Tribunal elects its Registrar for a term of five years. It elects a Deputy Registrar for a term of five years; it may also elect an Assistant Registrar. The Tribunal may provide for the appointment of such other officers as may be necessary.
Mr. Gritakumar E. Chitty (Sri Lanka) served as Registrar from October 1996 to June 2001, Mr Philippe Gautier (Belgium) from September 2001 to July 2019.
The general functions of the Registrar are set out in article 36 of the Rules:
"The Registrar, in the discharge of his functions, shall:
(a) be the regular channel of communications to and from the Tribunal and in particular shall effect all communications, notifications and transmission of documents required by the Convention, the Statute, the Rules or any other relevant international agreement and ensure that the date of dispatch and receipt thereof may be readily verified;
(b) keep, under the supervision of the President of the Tribunal, and in such form as may be laid down by the Tribunal, a List of cases, entered and numbered in the order in which the documents instituting proceedings or requesting an advisory opinion are received in the Registry;
(c) keep copies of declarations and notices of revocation or withdrawal thereof deposited with the Secretary-General of the United Nations under articles 287 and 298 of the Convention or Annex IX, article 7, to the Convention;
(d) keep copies of agreements conferring jurisdiction on the Tribunal;
(e) keep notifications received under article 110, paragraph 2;
(f) transmit to the parties certified copies of pleadings and annexes upon receipt thereof in the Registry;
(g) communicate to the Government of the State in which the Tribunal or a chamber is sitting, or is to sit, and any other Governments which may be concerned, the necessary information as to the persons from time to time entitled, under the Statute and the relevant agreements, to privileges, immunities or facilities;
(h) be present in person or represented by the Deputy Registrar, the Assistant Registrar or in their absence by a senior official of the Registry designated by him, at meetings of the Tribunal, and of the chambers, and be responsible for preparing records of such meetings;
(i) make arrangements for such provision or verification of translations and interpretations into the Tribunal's official languages as the Tribunal may require;
(j) sign all judgments, advisory opinions and orders of the Tribunal and the records referred to in subparagraph (h);
(k) be responsible for the reproduction, printing and publication of the Tribunal's judgments, advisory opinions and orders, the pleadings and statements and the minutes of public sittings in cases and of such other documents as the Tribunal may direct to be published;
(l) be responsible for all administrative work and in particular for the accounts and financial administration in accordance with the financial procedures of the Tribunal;
(m) deal with inquiries concerning the Tribunal and its work;
(n) assist in maintaining relations between the Tribunal and the Authority, the International Court of Justice and the other organs of the United Nations, its related agencies, the arbitral and special arbitral tribunals referred to in article 287 of the Convention and international bodies and conferences concerned with the codification and progressive development of international law, in particular the law of the sea;
(o) ensure that information concerning the Tribunal and its activities is accessible to Governments, the highest national courts of justice, professional and learned societies, legal faculties and schools of law and public information media;
(p) have custody of the seals and stamps of the Tribunal, of the archives of the Tribunal and of such other archives as may be entrusted to the Tribunal."