The Hagia Sophia, Secularism, and International Cultural Heritage Law
Turkey announced in July 2020 that it would turn the Hagia Sophia back into a mosque. The edifice has a long history, and is treasured, inter alia, for its non-denominational nature, showcasing multiple, overlapping religious layers. In fact, it had been a non-religious museum for 85 years. That overlap is a key reason for its listing as the centrepiece of the Historic Areas of Istanbul, on the World Heritage List created by the 1972 World Heritage Convention. While the World Heritage List contains functioning places of worship, the difference in the case of Hagia Sophia is its history of religious layers. Similar to the newly constructed Hindu temple at the site of a destroyed mosque in Ayodhya, India, the Turkish government's decision to turn Hagia Sophia back into a mosque appeals to a certain domestic political constituency. However, it also raises questions regarding its compatibility with International Cultural Heritage Law (ICHL).
The Hagia Sophia was originally built about 1,500 years ago (in 537 CE) as a Christian Orthodox cathedral. At the time of construction, it was the largest interior space in the world, a feat of architecture and engineering. It had a brief interlude as a Roman Catholic cathedral in the 13th century and remained the world's largest house of worship until 1520. It was converted into a mosque after the Ottoman conquest in 1453 by Mehmet the Conqueror and established as a museum by the secular Turkish Republic in 1934, opening for the public in 1935. In July 2020, a judicial decision by Turkey's Council of State annulled the 1934 museum conversion on the basis of Mehmet's original waqf (a legal form in Islamic law akin to the common law's trust), which determined that the site should function as a mosque. The decision was the culmination of a fifteen-year legal battle, and paved the way for a Presidential Decree reopening the site as a mosque.
This Insight discusses whether turning Hagia Sophia into a mosque violates ICHL—in particular, the World Heritage Convention—and how this treaty shapes discourses around religion and secularism. It also briefly explores which states may invoke Turkey's international responsibility.
Did Turkey Violate ICHL?
The 1972 World Heritage Convention, one of the world's most widely ratified treaties, governs the Hagia Sophia's status as a global icon. The World Heritage List contains 1,121 sites around the world. The Historic Areas of Istanbul, on the list since 1985, are of world significance (or, in the Convention's parlance, "Outstanding Universal Value"), because of the overlap of multiple civilizations. The question is whether, by privileging one of Hagia Sophia's layers, its use as a mosque contravenes the nature of the listing.
The Convention is ambiguous in its relationship to states' control over heritage and its meanings:
Article 4. Each State Party to this Convention recognizes that the duty of ensuring the identification, protection, conservation, presentation and transmission to future generations of the cultural and natural heritage . . . situated on its territory, belongs primarily to that State.
Article 6.1. Whilst fully respecting the sovereignty of the States on whose territory the cultural and natural heritage . . . is situated . . . the States Parties to this Convention recognize that such heritage constitutes a world heritage for whose protection it is the duty of the international community as a whole to co-operate. (emphasis added)
These two provisions showcase the tension between sovereignty and the idea that heritage represents humanity's collective values. Adding a site to the World Heritage List cannot happen without the territorial state's initiative; as such, Hagia Sophia is on the list because Turkey actively sought that outcome. Once the site is on the list, however, the unresolved question is who controls the meanings of the site and changes to its use. UNESCO may see it as their prerogative, but the Operational Guidelines to the Convention confirm that the state is responsible for the presentation of the site and its content, and the international community only has a "collective interest . . . to cooperate in the protection of this heritage." The same document further requires that states put in place legislative and regulatory measures to "assure the protection of the [site] from social . . . and other pressures or changes . . . ."
Ultimately, the transformation of Hagia Sophia into a mosque frames a typical dilemma between sovereignty and common values, the difference being that these values are not sufficiently defined. For ICHL, they might be religiously neutral cosmopolitanism; for countries like Turkey, these values can be religion as a standard bearer for pluralism. The Operational Guidelines are largely silent on the intersection of religion and heritage, except for cultural landscapes (which includes sacred areas, normally to Indigenous peoples) and cultural routes (which includes pilgrimage routes). The Guidelines acknowledge that religion and religious values are a key reason why these types of sites are valued, but they say nothing about conciliating religious and non-religious uses of the sites. Religion is important to get into the door of recognition as a World Heritage site, but is left at the same door once recognition is granted.
Thus, a key question raised is whether ICHL is neutral vis-à-vis religion and what neutrality/secularism means within the context of the Hagia Sophia case. Secularism here can mean that the law does not prescribe or prohibit the religious use or dimension of sites, leaving it to sovereign states to decide the use of sites (as long as they do not endanger them). But secularism could also mean that ICHL requires states to treat sites like the Hagia Sophia in a laic, non-religious manner.
Typically, when the religious use of a site means the exclusion of other, secular, uses, religious uses are not encouraged by UNESCO. More generally, UNESCO sees religious heritage as a way to "contribute to the rapprochement of cultures and harmonious relations among peoples." Arguably, heritage status largely secularizes religion because it understands religion as a cultural phenomenon. Religion as culture is necessarily non-exclusionary. Heritage values, when in conflict with religion, tend to prevail because they represent all of humanity, as opposed to the segment of believers. In that sense, ICHL may be seen as being primarily laic regarding sites like the Hagia Sophia. When a heritage site is associated with more than one religion, no religion should negate or overshadow the site's universal value.
Hagia Sophia's re-conversion into a mosque, a move decried by UNESCO, stands in tension with the secular stance of ICHL vis-à-vis sites with multiple religious layers. It signals a prioritization of one historical layer over all others and undermines interfaith and intercultural dialogue. As UNESCO's Director-General put it, Hagia Sophia's "status as a museum reflects the universal nature of its heritage, and makes it a powerful symbol for dialogue." If the conversion into a functioning mosque means erasing historic layers that are key to Hagia Sophia's value, it goes against the object and purpose of the World Heritage Convention. Only two sites have ever been removed from the World Heritage List; should Hagia Sophia be the third, it would be the first removal in the name of religion.
Who May Invoke the Responsibility of Turkey?
If the conversion is indeed in contravention to the World Heritage Convention, the next question is who may invoke Turkey's international legal responsibility. The International Law Commission's (ILC) Articles on the Responsibility of States for Internationally Wrongful Acts, which largely codify customary law, distinguish between injured and non-injured states, enabling non-injured states to invoke a wrongdoer's responsibility if the obligation breached is owed to all other states (erga omnes obligations). The right of non-injured states to invoke the responsibility of a state violating obligations erga omnes(partes) is well-established in the case law of the International Court of Justice, which recently confirmed this right in its January 2020 provisional measures order in The Gambia v. Myanmar genocide case. The World Heritage Convention's aim is to protect humanity's common heritage. Therefore, all states parties have a legitimate interest in having their common heritage protected and used in conformity with its universal value. Therefore, even as non-injured states, all parties to the World Heritage Convention could claim from Turkey the cessation of the use of Hagia Sophia as a mosque, and assurances and guarantees that its non-denominational nature will be preserved in the future.
The ILC Articles also provide that a state "is entitled as an injured State to invoke the responsibility of another State if the obligation breached is owed to . . . a group of States including that State, or the international community as a whole, and the breach of the obligation . . . specially affects that State." Are there any states that could claim to be directly/specially injured by Hagia Sophia's transformation into a mosque? Perhaps a state like Greece that feels closely associated to Hagia Sofia for historical and religious reasons? Or Christian Orthodox states that object to the transformation of a former Christian Orthodox church into a mosque? Or even all Christian states, irrespective of whether they are Orthodox? In answering these questions, one must not lose sight of the aim pursued by the obligation breached by Turkey. Rather than favouring Christianity, the point is to secure Hagia Sophia's neutral use for interfaith and intercultural dialogue, for all states in the globe. Besides, a similar question regarding specially-affected states exists in international human rights law, which also protects common values. In the past, scepticism has been expressed regarding the idea that a state can be directly/specially injured because of human rights violations against its nationals by a third state. Subscribing to this approach makes it more difficult to reach the threshold of direct injury in ICHL. As a result, responsibility towards "specially affected" states will likely be limited to more straightforward cases, such as transboundary World Heritage sites/monuments or archaeological looting.
Both the question of ICHL's neutrality vis-à-vis religion in the case of sites with multiple religious/historical layers and the concept of "specially affected" state remain open to multiple interpretations in international law. The transformation of Hagia Sophia into a mosque can be a litmus test with the potential to generate state practice contributing to the shaping of both ICHL and state responsibility law.
About the Authors: Lucas Lixinski is an Associate Professor at the Faculty of Law, UNSW Sydney, and Vassilis P. Tzevelekos is a Senior Lecturer at the School of Law and Social Justice, University of Liverpool.
 UN Educational, Scientific and Cultural Organisation (UNESCO), Convention Concerning the Protection of the World Cultural and Natural Heritage, Nov. 16, 1972, 1037 U.N.T.S. 151; and World Heritage Centre, Historic Areas of Istanbul, https://whc.unesco.org/en/list/356/.
 Jeffrey Gettleman, Hari Kumar, Modi Founds Temple on Mosque's Ruins, in Triumphal Moment for Hindu Base, N.Y. Times (Aug. 5, 2020), https://www.nytimes.com/2020/08/05/world/asia/modi-temple-ayodhya.html.
 Aylin Dal, Kemal Karadag, Turkey: Court strikes down Hagia Sophia museum decree, Anadolu Agency (July 10, 2020), https://www.aa.com.tr/en/turkey/turkey-court-strikes-down-hagia-sophia-museum-decree/1906171.
 Presidency of the Republic of Turkey Directorate of Communications, Presidential Decree on the opening of Hagia Sophia to worship promulgated on the Official Gazette, https://www.iletisim.gov.tr/english/haberler/detay/presidential-decree-on-the-opening-of-hagia-sophia-to-worship-promulgated-on-the-official-gazette-of-the-republic-of-turkey/.
 The Operational Guidelines for the Implementation of the World Heritage Convention, UNESCO Doc. 43 COM 11A (2019), ¶ 15.
 Id. ¶ 98.
 UNESCO World Heritage Centre, Heritage of Religious Interest: UNESCO Initiative on Heritage of Religious Interest, https://whc.unesco.org/en/religious-sacred-heritage/.
 Lucas Lixinski, Religious Cultural Heritage: The Law and Politics of Conservation, Iconoclasm, and Identity, in Heritage at the Interface: Interpretation and Identity (Glenn Hooper ed.) (2018), DOI:10.5744/florida/9780813056579.003.0009.
 UNESCO, UNESCO statement on Hagia Sophia, Istanbul (July 10, 2020), https://en.unesco.org/news/unesco-statement-hagia-sophia-istanbul.
 These are the Arabian Oryx Sanctuary (Oman), and the Dresden Elbe Valley (Germany).
 International Law Commission, Draft Articles on Responsibility of States for Internationally Wrongful Acts, U.N. Doc. A/56/10, CHP.IV.E.1 (Nov 2001) [hereinafter ARSIWA].
 Id. art. 48(1).
 ICJ, Application of the Convention on the Prevention and Punishment of the Crime of Genocide (The Gambia v. Myanmar), Order of Provisional Measures (Jan. 23, 2020), ¶ 41.
 ARSIWA, art. 48(2)(a).
 Id. art. 42(b)(i).
 Giorgio Gaja, Is a State Specially Affected When its Nationals' Human Rights Are Infringed, in Man's Inhumanity to Man. Essays on International Law in Honour of Antonio Cassese 373, 381-382 (LC Vohrah et al. eds.) (2003).