[2] For nearly a century after the end of English rule in 1684, Tangier was primarily a military town, the main fortified outpost on the Moroccan Sultanate's side of the Strait of Gibraltar.

[7]: 360  In 1840, a Dahir (decree) of Sultan Abd al-Rahman mandated them to establish a Sanitary Council (French: conseil sanitaire),[8]: 306  chaired by the envoys of the represented nations on a rotating basis in the name of the Makhzen.

[10]: 272  In 1887, Greek-American community leader Ion Hanford Perdicaris advocated a special status for Tangier as a neutral free port under the great powers' joint control.

That same year, a secret treaty between France and Spain acknowledged Tangier's special status and thus marked the first official prefiguration of later formal international arrangements.

[3]: 119  The Act of Algeciras also resulted in the creation of a dual police force under foreign control, the Tabor divided between French and Spanish components,[3]: 236  respectively in charge of public order outside and inside the city limits.

Later that year, Article 7 of the Treaty Between France and Spain Regarding Morocco stipulated that Tangier would be granted a special status and defined its geographical boundaries.

[1]: 17 [7]: 363  Meanwhile, Tangier still operated under an ad hoc governance regime with a Sultan-appointed governor, the Naib reduced to a largely ceremonial role since Morocco under the protectorates no longer had an autonomous foreign policy, the extraterritorial courts under the respective foreign delegations (downgraded back to consulate status for the same reason), the Sanitary Council, the Hygiene Commission, the French and Spanish Tabors, and assorted specialized committees.

The entry into force of the Paris Convention was further delayed by translation challenges,[8]: 318  so that the Tangier International Zone eventually started in 1 June 1925 under a Dahir of 15 May 1925.

[17]: 232  Simultaneously, the tasks of prior institutions including the Sanitary Council and Hygiene Commission were taken over by the new International Administration, even though the bodies themselves continued to exist for a few more years.

[7]: 361  The Paris Convention was proposed for ratification to the other powers that were party to the Algeciras Conference, except Germany, Austria and Hungary, disempowered by the peace treaties (respectively of Versailles, Saint-Germain and Trianon), and the Soviet Union, then estranged from the international system.

[17]: 233  It was ratified by Belgium (on 6 December 1924),[7]: 364  Sweden, the Netherlands (on 5 October 1925), and eventually by Portugal (on 28 January 1926),[18] putting an end to an awkward early period during which the Committee of Control practically could not reach a quorum.

[8]: 321  That revision also allowed the final abolition of Tangier's former ad hoc institutions, the Sanitary Council and Hygiene Commission, which Italy had previously insisted to maintain.

[8]: 329  The Zone's key institutions, the Committee of Control and Legislative Assembly, were abolished on 3 November 1940,[7]: 371  triggering a diplomatic dispute between Britain and Spain that led to a further guarantee of British rights and a Spanish promise not to fortify the area.

[7]: 373  It concluded with a temporary Anglo-French Agreement of 31 August 1945, in which the two powers made arrangements for the re-establishment of the Zone's international institutional framework, invited the United States and the Soviet Union to join it, and reversed the advantages that Italy had secured under the 1928 Protocol.

[8]: 331 Following the end of the French protectorate on 2 March 1956 and of the Spanish one on 7 April 1956, the Committee of Control of the Tangier Zone met in June 1956 and proposed a protocol for a temporary regime, which was signed by Moroccan Foreign Minister Ahmed Balafrej on behalf of Sultan Mohammed V in Rabat on 5 July 1956.

As a consequence, the position of Administrator was abolished and replaced on 10 July 1956 by that of a Moroccan governor or Amel, which was immediately assumed by the Mendoub Ahmad at-Tazi.

[7]: 380  Balafrej insisted that, while the abolition of the international status was a matter of negotiation with the foreign powers represented in the Committee of Control (namely Belgium, France, Italy, the Netherlands, Portugal, Spain, the UK, and the United States), the future arrangements were not and would be decided solely by the Moroccan authorities.

[29] The resulting protocol signed on 29 October 1956 returned Tangier to full Moroccan sovereignty with immediate effect, while the operation of its international institutions was extended for practical purposes only until the end of 1956.

[36] The assembly's membership was set as follows: 4 French, 4 Spanish, 3 British, 2 Italians (3 after 1928, 1 after 1945), 1 American (seat unoccupied until 1940,[37] 3 after 1945), 1 Belgian, 1 Dutch, 1 Portuguese, 6 Muslims, and 3 Jews.

[8] After World War II, a new home was built for the Legislative Assembly in the Marshan neighborhood of Tangier, across the street from the Mendoub's Residence.

[17]: 236  Unlike other institutions of the zone, the Mixed Courts continued to function under the Spanish occupation of Tangier during World War II.

[39]: 116 Following the convention of November 1952, the renamed International Jurisdiction included 2 judges from France, 2 from Spain, and 1 from each of Belgium, Italy, Morocco, the Netherlands, Portugal, Sweden, the UK, and the U.S., as well as Spanish and French prosecutors.

American citizens remained under the pre-1923 extraterritorial jurisdiction of the consular court of the United States, except for matters of property title and Islamic law.

[28]: 516  The State Bank of Morocco, whose head office was in Tangier, remained under the jurisdiction of a special tribunal created by Article 45 of the Act of Algeciras of 7 April 1906,[28]: 516  from which appeals went to the Federal Supreme Court of Switzerland in Lausanne.

The initial economic effect of the creation of the International Zone was sharply negative, because the Spanish protectorate authorities discouraged commerce with it and thus Tangier lost most of its traditional hinterland.