Paragraph 1 of Article XXI establishes the date of entry into force for the Convention. Specifically, this paragraph states that the Convention shall enter into force 180 days after the date of the deposit of the 65th instrument of ratification, but in no case earlier than two years after its opening for signature. This means that the earliest the Convention will enter into force is 13 January 1995, i.e. two years after 13 January 1993, the date the Convention was opened for signature. For this to occur, 65 states will have to ratify the Convention by 17 July 1994, i.e. 180 days before the two-year starting point. The purpose of the two-year delay is to provide the Preparatory Commission with time to set up the Organization and develop detailed implementing procedures, and to provide states, especially those with large chemical industries, with sufficient time to establish domestic legislation and ratify the Convention. The purpose of the 180-day delay is to provide sufficient advance notice to the (provisional) Technical Secretariat to prepare for activities it must conduct soon after entry into force, e.g. inspections of chemical weapons production facilities.
Paragraph 2 of Article XXI establishes the date of entry into force for those States that join the Convention after it enters into force. Specifically, this paragraph states that for States whose instruments of ratification or accession are deposited subsequent to the entry into force of this Convention, it shall enter into force on the 30th day following the date of deposit of their instrument of ratification or accession.