The countries which are now members of INTERPOL may have become members of the Organization in either one of two ways.
Membership pursuant to Article 45 of the Constitution
This provision applies to the countries that were members of the International Criminal Police Commission before the 1956 Constitution entered into force. Article 45 of INTERPOL’s Constitution stipulates that all “bodies representing the countries listed in Appendix I” to the Constitution shall be deemed to be members of INTERPOL “unless they declare through the appropriate governmental authority that they cannot accept” the Constitution. Such declarations had to be made within six months of the date of entry into force of the Constitution.
On 17 September 1956, the Secretary General wrote to the Heads of the National Central Bureaus of all the countries referred to in Article 45 reminding them that, if their countries could not accept the new Constitution, they had to signify non-acceptance by
13 December 1956 through the appropriate government authority .
The same procedure had been applied with regard to those countries that joined the ICPC between 1923 and 1946 when the 1946 Constitution of the International Criminal Police Commission was adopted.
Membership pursuant to Article 4 of the Constitution
Article 4 concerns countries wishing to join INTERPOL after 13 December 1956. Under Article 4 of the Constitution, after that date, the appropriate government authority of any countries wishing to join INTERPOL must submit a request for membership to the Secretary General. Membership is subject to approval of the request by a two-thirds majority of the General Assembly.