The United Nations Convention on the law of the sea provides that the establishment of the outer limits of the continental shelf beyond 200 nautical miles and its delimitation between neighboring States are separate processes. This is reflected in article 76(10) of the Convention, which provides that the provisions of article 76 are without prejudice to the question of delimitation of the continental shelf. Article 9 of Annex ii to the Convention enjoins the Commission on the Limits of the Continental Shelf (clcs) that its actions shall not prejudice matters relating to the delimitation of boundaries between States. The Commission has implemented the latter provision through Rule 46 of and Annex i to its Rules of Procedure. Paragraph 5(a) of Annex i implies that the consideration of a submission of a coastal State on the outer limits of the continental shelf by the Commission may be blocked by another State and this has happened in practice in a considerable number of cases. This implies that a coastal State will not be in position to establish final and binding continental shelf limits on the basis of the recommendations of the Commission, as is envisaged by article 76 of the Convention. Creating certainty about the extent of the continental shelf, and hence the limits of the Area, is one of the key objectives of the Convention. The Convention itself does not provide for the possibility that other States may block the consideration by the Commission of submissions of coastal States. The paper considers whether paragraph 5(a) of Annex i to the Commission’s Rules of Procedure has provided the proper approach to implementing article 9 of Annex ii to the Convention, what options are available to coastal States whose submission has been blocked in the clcs and whether Annex i to the Convention might be amended by the Commission.