Beyond Ownership: An Evolving Framework for the Restitution of Cultural Objects

Abstract

While the rule that stolen or unlawfully exported cultural objects should be returned has a solid basis in public international law, cross-border restitution in practice remains complex. Even where an artefact has been located and identified – a major first hurdle – numerous legal obstacles persist, most notably the non-retroactivity of treaties. Drawing on recent regulations, evolving practice and case law, this article argues that the traditional ownership-based approach to restitution, with its focus on economic rights, has become increasingly inadequate in light of the recognised heritage value of cultural objects as expressions of collective identity. By offering an overview of four distinct yet overlapping approaches to restitution, it demonstrates how the legal framework is undergoing significant transformation. To that end, it traces the early development of restitution norms in public international law and examines the traditional private-law ownership model; an ethical approach based on soft-law instruments; a human-rights-based approach emphasising the right to enjoy and access culture; and a criminal-law approach that conceptualises the trafficking and looting of cultural objects as forms of international crime, entailing a shift in the burden of proof and a central role for provenance research.

I. Introduction

While the rule that stolen or unlawfully exported cultural objects should be returned has a solid basis in public international law, cross-border restitution in practice remains complex. Even if an artefact has been located and identified – often a major preliminary hurdle – numerous legal obstacles can stand in the way of restitution, most notably the non-retroactivity of treaties.

Nevertheless, times are changing, and the legal framework is rapidly evolving. This shift is reflected in recent international declarations calling for the restitution of cultural objects, such as the 2022 MONDIACULT Declaration, ¹ the 2024 Qingdao Recommendations, ² the 2025 Brasília Declaration of the BRICS Ministers of Culture ³ and the 2025 Algiers Declaration. ⁴ These instruments call for the development of legal and institutional frameworks for restitution, often framed as a right of source communities or states to enjoy their cultural heritage, and for enhanced provenance research (i.e., research into the ownership history of artefacts) or ‘capacity-building’ within museums and cultural institutions. ⁵

This change is also visible in museum practice. Whereas the preservation of cultural objects in major museums was still widely accepted as a justification for declining claims in the 2002 ‘Declaration on the Importance and Value of the Universal Museum’, this position has clearly lost ground. ⁶ Today, some of the very museums that endorsed that Declaration have undertaken provenance research projects, developed restitution policies and engaged in high-profile returns.

There is also groundbreaking case law. Until recently, new possessors who were unaware of the ownership history of misappropriated objects (their provenance) upon acquisition could often rely on a valid ownership title, particularly in civil-law jurisdictions. An example is the 2018 Amsterdam District Court's denial of a claim by Chinese communities to their eleventh-century Buddha statue, known as ‘Master Zhang Gong’. ⁷ The statue had been stolen in 1995 and subsequently acquired by a collector who argued that he was unaware of its illicit provenance and could therefore rely on Dutch private law to establish a lawful ownership title.

Today, it can be safely stated that this stance is incompatible with contemporary international cultural heritage law, which treats such claims not merely as matters of domestic private law but also as implicating the cultural rights of the original owners. A May 2024 ruling by the European Court of Human Rights on an ancient Greek statue acquired by the Getty Trust – the ‘Victorious Youth’, smuggled out of Italy in the 1960s – illustrates this development. In that case, the Court confirmed Italy's right to seize the statue through a criminal-law approach, notwithstanding the considerable time that had passed since its acquisition by the Getty, and effectively applied contemporary due diligence standards to a sale in the early 1970s. ⁸ The contrast between these two rulings – one by a domestic civil court and the other by an international human rights court – is striking. It underscores not only the evolution of norms but also the diversity of legal settings and the fragmentation of the law in the field of restitution.

This contribution argues that, because the heritage value of cultural objects lies at the heart of most restitution claims, the approach framing such disputes primarily as matters of ownership and private law, with its focus on individual economic rights, has proven inadequate. Divergences between jurisdictions in ownership law, moreover, mean that the unlawfulness of the taking is not attached to the object as it moves across borders. This has prompted the emergence of alternative approaches and new legal models for the restitution of cultural objects. What follows offers an overview of different existing approaches. ⁹

Section III discusses the traditional ‘ownership approach', in which restitution claims are treated as cases concerning lost property governed predominantly by private law. Section IV examines the ‘ethical approach’, based on non-binding soft-law instruments that acknowledge the identity value of cultural objects but frame restitution primarily as a matter of morality rather than law. This approach, prevalent in the context of Nazi-looted art and colonial-era takings, partly overlaps with a human-rights-based approach to restitution, discussed in Section V. By invoking, inter alia, the right to enjoy and access one's own culture, restitution is here framed as a matter of fundamental human rights – an approach reflected in several of the recent declarations mentioned above.

Section VI addresses a ‘criminal-law approach', which conceptualises the trafficking and looting of cultural objects as forms of international crime in which restitution may result following forfeiture of the object. Although primarily aimed at combating trafficking, this approach is of broader relevance, as it entails a significant shift in focus towards provenance research and mandatory due diligence standards for the trade. In doing so, it effectively reallocates the burden of proof to new possessors and holding institutions, a development examined further in Section VII. Since many contemporary restitution claims concern past losses, the analysis begins, in Section II, by outlining the development of international legal norms relating to the restitution of cultural objects.

II. Protection and Restitution: Early Developments

Cultural objects – defined as items of importance to archaeology, prehistory, history, literature, art or science – have for long enjoyed protected status in public international law because of their heritage value as symbols of cultural identity. ¹⁰ It is precisely this identity that is often targeted in looting practices. Identity was at stake in Nazi looting practices and, similarly, in colonial contexts. European powers, for example, justified their presence and dispossession of cultural objects in Africa by referring to their duty to bring the ‘blessings of civilisation’ to the people they considered uncivilised. ¹¹

The notion that pillaging other people's cultural objects in times of armed conflict is uncivilised is also very ancient. In the European setting, it gained legal significance through the writings of the founders of international law. To cite Grotius:

[t]here are some things of such a nature, as to contribute, no way, to the support and prolongation of war. … (s)uch are porticos, temples, statues, and all other elegant works and monuments of art. ¹²

Grotius is often cited in relation to the ius praedae – the right to spoils. However, this passage represents a clear ‘modification’ of that rule. While international law (even today) allows the seizure of objects that make an effective contribution to military action, it excludes certain cultural objects. ¹³

The corollary of the prohibition on seizing cultural objects is a duty to return (restitute) those taken in violation of that rule. ¹⁴ Over time, this obligation gained force as an international standard. ¹⁵ In this development, the 1815 Congress of Vienna following the Napoleonic wars is frequently quoted as a turning point at which the European powers agreed, as a principle of justice, on an obligation to restitute looted artefacts. ¹⁶ During the negotiations, Viscount Castlereagh, speaking on behalf of the British delegation, argued that the spoils of war should be returned to their place of origin in order to ‘effectuate what justice and policy require’. ¹⁷ Similarly, the 1813 ruling of the Marquis de Someruelas, ordering the return of artefacts seized as war booty in the Anglo-American War, held that the immunity of cultural objects in times of war formed part of the ‘Law of Nations, as practised by all civilised countries’. ¹⁸

This development continued, and the special protected status was codified in the first multilateral treaty, the 1899 Hague Regulations concerning the Laws and Customs of War on Land. ¹⁹ Eventually, following the massive looting of cultural objects during the Second World War, dedicated treaties were adopted: the 1954 Hague Convention for the Protection of Cultural Property in the Event of Armed Conflict and its Protocol and the 1970 United Nations (UN) Educational, Scientific and Cultural Organization (UNESCO) Convention on the Means of Prohibiting and Preventing the Illicit Import, Export and Transfer of Ownership of Cultural Property. ²⁰

In broad terms, these treaties establish that cultural objects enjoy special protection, in times of both armed conflict and peace, that the transfer of cultural objects without authorisation by the national authorities is unlawful ²¹ and that cultural objects exported in violation of this rule should be returned, ²² possibly upon compensation to good-faith new possessors – ‘innocent purchasers or persons holding valid title’ in terms of the 1970 UNESCO Convention. ²³

While the prohibition on the seizure of cultural objects in times of war is recognised as having customary law (and therefore binding) status – as confirmed during the Nuremberg trials ²⁴ – and the unlawfulness of unauthorised export of protected cultural objects is widely acknowledged, ²⁵ the legal consequences of these norms for the status of cultural objects are less straightforward. This is because the relevant treaty provisions on restitution in the UNESCO Conventions are notably vague, leave the issue of restitution largely to states to arrange at the domestic level, ²⁶ and apply only after adoption and implementation in national law. The complications arising from this state of affairs are discussed next.

III. The Private-Law Approach: Lawful Ownership?

Against the background of the public international law framework outlined above, restitution disputes have traditionally been resolved through reliance on ownership title and, thus, on private law. That cultural objects are not merely possessions is acknowledged in most legal systems. Under Roman law, for instance, certain cultural objects were inalienable (res sacrae or res extra commercium), and in most jurisdictions, similar rules exempting cultural objects of local importance from ordinary property law rules exist: they cannot be traded or exported like other goods. Such special protection, however, tends to be limited to nationally protected cultural heritage.

International private law – being a domain of domestic law – should then, in principle, guide judges to a just outcome. ²⁷ At this level, two structural problems arise. First, ownership issues concerning movable goods are typically governed by the law of the country where the object is located (lex rei sitae), enabling the laundering of looted artefacts through jurisdictions that permit the transfer of title. Particularly in civil-law countries (most European jurisdictions), title to stolen goods may pass after the lapse of time (acquisitive prescription) or through an acquisition in good faith. Although common-law jurisdictions (e.g., England and most of the USA) accord relatively strong rights to the dispossessed former owner, based on the nemo dat rule, limitation periods on claims often obstruct restitution. Over time, legal reality tends to adapt to the prevailing situation, rendering claims inadmissible.

A second problem, already touched upon above, is that foreign public law does not automatically apply in another jurisdiction, while (administrative) export laws or those that render cultural objects inalienable often underpin the illegality of the taking.

To address these issues, the 1995 International Institute for the Unification of Private Law (UNIDROIT) Convention was adopted to harmonise private law and ensure the return of stolen or unlawfully exported cultural objects as foreseen in the 1970 UNESCO Convention. ²⁸ It introduces a model under which title to cultural objects cannot easily pass after theft or unlawful export, notably by providing harmonised and extended limitation periods for claims. Nevertheless, even for cultural objects under ‘enhanced’ protection it allows states to set a 75-year time limit for claims, which does not accommodate claims to Nazi-looted art or colonial-era takings. ²⁹ Another concession to civil-law countries is that new possessors are entitled to ‘fair and reasonable’ compensation if they exercised due diligence in researching the provenance of the artefact upon acquisition.

While wide adoption of the UNIDROIT Convention would support restitution prospectively, most of today's claims deal with historical losses, and many market or holding countries have not acceded to that Convention and have only recently become parties to the 1970 UNESCO Convention. ³⁰ As a result, the fragmented situation persists, as illustrated by the Chinese Buddha case mentioned in the introduction. The Netherlands, where the statue was found in the hands of a collector, is not party to the 1995 UNIDROIT Convention and acceded to the 1970 UNESCO Convention in 2009. Consequently, for claims to cultural objects lost before that year, ordinary private law applies, favouring new possessors.

In the meantime, the reliance on lawful title under domestic private law where an object surfaces or was traded as the decisive criterion for cross-border claims is increasingly being challenged. The contours of an alternative practice are emerging in rulings in which courts have given priority to the law of the state of origin. ³¹ A noteworthy example is the continuation of the litigation concerning the Buddha statue: after proceedings in the Netherlands ended, litigation in China – initiated in Sanming already in 2015 – continued, and the restitution claim brought by the deprived communities was upheld. ³² By reference to the object and purpose of the 1970 UNESCO Convention and the 1995 UNIDROIT Convention (neither of which applied directly), the court held that, in cultural property disputes, the law of the country where the artefact was stolen should govern questions of ownership, rather than the law of the country where the object surfaced or was last traded. ³³ This meant that Chinese law applied, under which the statue constituted inalienable communal property and ownership could therefore not have passed.

This prioritisation of the law of the country of origin in determining ownership potentially has far-reaching implications, given that laws declaring certain cultural objects inalienable often date back many decades. Nevertheless, it reflects an international standard promoted by the Institut de Droit International as early as 1991. ³⁴ The Belgian Code of Private International Law (2004) likewise provides for a special conflict-of-laws rule applicable to cultural objects that unlawfully left the territory of the country of origin. ³⁵ Moreover, the 2023 UNESCO Model Provisions on the Prevention and Fight against Illicit Trafficking of Cultural Property, developed to guide states in their implementation of the 1970 UNESCO Convention, also propose that

When ruling on claims for restitution or on requests for return of cultural property, the judicial or administrative authority of the State addressed should apply the law of the State of origin on the control of the movement and ownership of cultural property. ³⁶

A special conflict-of-laws rule for cross-border ownership claims to cultural objects – under which the law of the country where the loss occurred (lex originis) governs questions of title – is thus emerging as a private-law tool enabling courts to reach outcomes in line with international cultural heritage law.

Whether, and to what extent, this approach will gain broader acceptance in civil-law jurisdictions remains to be seen. The reality is that trade in unprovenanced cultural objects has long been the norm rather than the exception, and where new possessors have acquired lawful title under prevailing private law, denying compensation may result in a clash of interests and norms. It is therefore likely that acceptance of the lex originis will be limited to future acquisitions, once again leaving many historical losses without effective legal remedy.

IV. Bridging Gaps: An Ethical Approach

In response to these limitations in the traditional legal model, an ethical approach has gained traction. Guided by non-binding soft-law instruments and professional ethical guidelines that acknowledge the particular cultural and identity values involved, this approach advocates the resolution of ‘moral’ claims through out-of-court settlements. Soft-law instruments in this field vary widely. Some standards are general and aspirational in character, such as the International Council of Museums (ICOM) Code of Ethics, which provides that museums should neither display nor acquire cultural objects that lack full provenance – a standard that is hardly ever met in practice today. ³⁷ Other instruments focus on specific forms of looting and are more effective in practice than binding law.

These instruments tend to follow a similar pattern: they advocate equitable solutions to title disputes, prioritising the interests of dispossessed owners, the use of alternative dispute resolution mechanisms to resolve claims and proactive provenance research by museums. This ethical approach has proven particularly important in the field of Nazi-looted art and also increasingly in relation to colonial-era claims, discussed hereunder.

A. Nazi-Looted Art

The background to Nazi-looted art lies in the widespread looting carried out by the Nazis during the Second World War, most notably from Jewish owners as part of the genocidal persecution. After the war, a restitution framework was established to reverse the various forms of looting, relying on (i) external restitution to the countries from which artefacts had last been removed and (ii) internal restitution to dispossessed owners, for which states enacted special legislation suspending ordinary private-law rules. ³⁸ Due to the limited timeframes within which claims could be filed, these post-war restitution laws now play virtually no role in practice.

In the late 1990s, the apparent injustice faced by dispossessed families – who encountered family heirlooms on museum walls but whose claims were often legally barred – returned to the political agenda. In 1998, more than 40 states adopted the Washington Conference Principles on Nazi-Confiscated Art, introducing the now widely recognised – yet non-binding – standard that former owners or their heirs are entitled to a ‘just and fair solution’, depending on the circumstances of each case. ³⁹ Together with later instruments, the Principles also emphasise the importance of proactive provenance research by museums and alternative dispute resolution mechanisms for resolving claims. Around the turn of the century, and in that spirit, special governmental committees were established in the United Kingdom, Austria, Germany, France and the Netherlands to assess claims relating to artefacts in public (or state) collections. ⁴⁰ More recently, Switzerland ⁴¹ and Belgium ⁴² have also announced the establishment of such committees.

The ‘just and fair’ rule calls for redress for dispossessed private owners who lost their artefacts through Nazi persecution. Yet what this means exactly remains less contested, even after 25 years. Most notably, views differ as to what constitutes ‘Nazi-looted art’. While it is generally accepted that confiscations, thefts and forced sales fall within this category, sales conducted in neutral countries by refugees to third parties may likewise be regarded as forced sales. The so-called Best Practices, published to mark the 25th anniversary of the Washington Principles, endorse this latter interpretation. ⁴³

B. Colonial-Era Takings

The return of cultural objects removed in the context of Western imperialism gained momentum more slowly, despite the United Nations General Assembly already in 1973 calling on states to ‘return works of art to countries victims of expropriation’, referring to the right of new states to (cultural) self-determination. ⁴⁴ Although this seemed a promising beginning, former colonial powers generally failed to act upon this call, arguing that colonial takings constituted a sui generis category. It should be recalled that, for a long time, international law was an exercise conducted among a small group of so-called (European) ‘civilised nations’. ⁴⁵

Attitudes changed in 2017, when French President Emmanuel Macron gave the starting signal for renewed engagement by stating that it is no longer acceptable that most of Africa's cultural heritage remained in Europe, beyond the access of Africans themselves. ⁴⁶ Although actual returns from France have so far been limited, Germany has taken a leading role. In 2022, for instance, a historic agreement was concluded between Germany and Nigeria, under which all Benin Bronzes held in German museums were returned in ownership to the Nigerian state. ⁴⁷ These sculptures, mostly ancestral figures, had been looted at the end of the nineteenth century during the British military expedition against the royal palace of the Benin Kingdom (in present-day Nigeria).

The Dutch government likewise took action: policy guidelines for the Dutch State Collection were adopted, and in November 2022, the Commissie Koloniale Collecties was established to advise on claims. ⁴⁸ This policy framework rests on the principle of unconditional return of cultural goods from former Dutch colonies that can be shown to have been involuntarily lost and that have come into the possession of the Dutch State. ⁴⁹ Where proof of involuntary loss is lacking – which may be difficult to establish today – or where a request is made by a country that was not a former Dutch colony, return may follow after a balancing of interests. The relevant interests cited in the Dutch policy include the cultural significance of the object for the country of origin, the communities involved and the Netherlands (including for ‘Dutch people with roots in the countries of origin’), as well as the conditions for its future preservation and public accessibility. ⁵⁰

In this vein, on 6 July 2023, the first returns to Indonesia and Sri Lanka were announced, and more have followed. ⁵¹ Interestingly, some of these items concern (ritual) weapons taken during military actions, such as a Balinese keris and a cannon and knife from Sri Lanka, which – even under today's standards – could have been regarded as legitimate war booty at the time as military equipment. ⁵² That this issue was not raised underscores that the heritage value of cultural objects today – rather than the unlawfulness of the loss – is regarded as key, in line with a human-rights-based approach, as discussed below.

V. A Human Rights Approach

As seen above, the international legal obligation to return looted cultural objects developed through the laws of war, with restitution being the preferred form of reparation after pillage in times of war or foreign occupation. Since the adoption of the 1970 UNESCO Convention, this has been extended to include cultural objects looted in peacetime. In this conventional model, however, claims are often inadmissible, as discussed in Sections II and III, due to the fact that the unlawfulness of the taking (and its moment) is key for title issues and treaties are non-retroactive. In that conventional (or traditional) model, nation-states are treated as the ‘owners’ of their national cultural property. This may lead to conflicts if artefacts are culturally significant to a specific group or individual who is not (or no longer) represented by the modern state from which the items were taken. For instance, the looting of Jewish citizens by the Nazis was conducted or condoned by the victims’ national governments. Consequently, the ethical approach in the Washington Principles directly addresses private former owners rather than the state from which the objects were looted.

But human rights law instruments also vest rights in cultural objects, particularly to individuals and groups, notably the right to culture in Article 15(1)(a) of the 1966 International Covenant on Economic, Social and Cultural Rights (ICESCR). ⁵³ According to the 2009 General Comment on the right to culture of the supervisory treaty body under this Covenant, this has come to include ‘access to cultural goods’. ⁵⁴ Access to cultural objects is, in other words, an essential dimension of human rights and claims to lost cultural objects may thus also be approached from that perspective.

A. The Example of the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP)

A clear example of a human rights law approach to restitution can be found in the 2007 UNDRIP. ⁵⁵ It contains a right of redress, ‘which may include restitution … with respect to their cultural, intellectual, religious and spiritual property taken without their free, prior and informed consent or in violation of their laws, traditions and customs’. ⁵⁶ Depending on the cultural significance of the object, such redress may vary from a right to ‘access and control’ to a straightforward right to repatriation. ⁵⁷ To fulfil this aim, states are expected to provide assistance – ‘effective mechanisms in conjunction with Indigenous peoples’ – in addressing claims. In this regard, the 2020 Report of the Expert Mechanism on the Rights of Indigenous Peoples also concludes that

'States should enact or reform legislation on repatriation in accordance with [UNDRIP, EC] with the full and meaningful participation of Indigenous peoples and the safeguarding of free, prior and informed consent’; and that ‘Museums, universities and other collecting institutions must become partners in ensuring that Articles 11, 12 and 31 of the Declaration are respected and upheld. Museums must develop relationships of collaboration and trust, and seek out and respect Indigenous peoples’ knowledge, protocols, traditional laws and customs regarding items in their collections’. ⁵⁸

UNDRIP's provisions on cultural rights are considered an implementation of the (binding) right to culture in Article 15(1a) of the ICESCR. ⁵⁹ Moreover, while the UNDRIP was adopted as a non-binding declaration, according to numerous scholars the right of Indigenous peoples to their cultural heritage has, today, crystallised into customary international law. ⁶⁰ For the time being, however, this seems not to be the view of Western European museums. ⁶¹ Irrespective of its binding status, states that have signed the UNDRIP are expected to work towards fulfilling its aims and to assist Indigenous peoples in providing ‘redress through effective mechanisms’ and to ‘enable the access and/or repatriation of ceremonial objects and human remains in their possession through fair, transparent and effective mechanisms developed in conjunction with the Indigenous peoples concerned’. Recent practice indeed signals a change in that respect.

The 2018 Colombian Constitutional Court ruling on the ‘Quimbaya Treasure’ stands out, as it confirms the view that under contemporary standards of international law, referring to UNDRIP as well as the 1970 UNESCO and 1995 UNIDROIT Conventions, Indigenous communities are entitled to their lost cultural objects. In its ruling, the court ordered the Colombian government to pursue, on behalf of the Quimbaya people, the restitution by Spain of a golden treasure lost at the close of the nineteenth century. ⁶² Recent return decisions in Europe, also referring to the UNDRIP, bolster that interpretation. The first worth mentioning is a decision by the Swedish government to return to the Yaqui people in Mexico cultural objects that were taken during scientific fieldwork in the 1930s. ⁶³ A second decision concerns a German return of cultural objects, taken in the 1830s by missionaries, to the Indigenous Kaurna people in Australia. ⁶⁴ In her speech at the handover ceremony in the latter case, in May 2024, the German Minister of Foreign Affairs expressly acknowledged the rights of Indigenous peoples to their lost cultural objects. Moreover, a 2025 decision by the Dutch government likewise refers to the UNDRIP in its argumentation that cultural objects taken from the Indigenous Pueblo del Sur nation in the USA should be returned to them. ⁶⁵

B. An Evolving Model for Restitution? ⁶⁶

These developments may signal the coming into existence of a human rights model for claims that distinguishes itself by relying on a continuing cultural link between cultural objects and people who identify with these objects.

The growing importance of human rights law for restitution issues, is also broader than the field of Indigenous peoples’ cultural rights, as highlighted by the involvement of human rights bodies in this field over the last decade. In its 2016 Resolution, for instance, the UN Human Rights Council calls for ‘enhanced international cooperation in preventing and combating the organized looting, smuggling and theft of and illicit trafficking in cultural objects and in restoring stolen, looted or trafficked cultural property’. ⁶⁷ The message here is that people who are left without their cultural objects after looting practices are deprived of certain human rights.

In contrast to the traditional approaches to restitution that rely on the unlawfulness of a loss in the past, this model relies on the unlawfulness of remaining separated from such objects – that is, not having access to or control over them may amount to a continuing human rights violation, irrespective of ownership title under private law.

Another notable aspect is that it appoints (Indigenous) communities as ‘right holders’, whereas in the interstate system of UNESCO Conventions, national states are addressed as ‘right holders’ (owners) of their cultural property. This does not negate the role governments have as custodians of the interests of their citizens, but it does highlight the importance of the participation of these communities in decisions over their cultural heritage. Since this approach centres around the broader right of access and control, not per se on ownership, this right could also be understood as extending to the (preliminary) phase of provenance research and questions how collections are exhibited and kept. Particularly if there is a strong connection with specific communities (e.g., religious items), research should ideally be undertaken in consultation with source communities

VI. A Criminal-Law Approach: Return After Seizure

The last ‘model’ to obtain cross-border restitution is by reliance on criminal law. Restitution, in this approach, is the result of the seizure of an artefact after the violation of a prohibition on import, on placing on the market, or on the possession of unlawfully exported or looted cultural property. Where sanctioned under criminal law, this may trigger forfeiture, resulting in return to the dispossessed owner through interstate (diplomatic) channels. Although it is primarily relevant to contemporary looting practices and trafficking, it affects the field in a broader sense.

Upon the adoption of the 1970 UNESCO Convention, which in Article 13 lays down the requirement to adopt measures to prevent the illicit trade in cultural objects at the domestic level, the idea was that states would adopt import prohibitions for cultural objects lacking valid export licences. ⁶⁸ In the absence of clear obligations or uniform standards in that regard, however, market states until recently generally adopted a ‘laissez-faire' policy. ⁶⁹ As Peters observes in this respect ‘most of the States Parties to the Convention have enacted only national export laws, which apply to their own cultural heritage; they have failed to create import provisions that would protect other states’ cultural heritage’. ⁷⁰

Nevertheless, some states indeed adopted import prohibitions in their implementation legislation, notably the USA, which was among the first market states to adopt the 1970 UNESCO Convention (in 1986). ⁷¹ The criminal-law approach has thus been mostly visible in the USA, where in high-profile cases, artefacts have been seized from major museums – an approach that has interestingly also been deployed in cases involving Nazi-looted art. ⁷² Another example concerning an earlier loss is the 2025 Australian High Court ruling on forfeiture and the return to Bolivia of a pre-Columbian artefact that was illicitly exported more than 70 years ago, after it was seized following import into Australia. ⁷³

A. New Regulations

The criminal-law approach gained traction in the wake of the conflicts in Iraq and Syria, prompting the involvement of the UN Security Council, which called on states to prohibit the trade in antiquities looted in those specific areas during the conflict. ⁷⁴ This also triggered the framing of trafficking in cultural objects as a form of transnational crime within the meaning of the UN Convention against Transnational Organized Crime. ⁷⁵ As noted by Blake, treating trafficking as a form of transnational organised crime seems to offer a better route for combating the illicit trade, given the limited effectiveness of cultural heritage treaty regimes in preventing such trade and supporting the return of illicitly trafficked items. ⁷⁶

In this spirit, in 2017, the Council of Europe Convention on Offences relating to Cultural Property (the 2017 Nicosia Convention) was adopted, as the first international convention to take a criminal-law approach to the protection of cultural property. ⁷⁷ It establishes dedicated criminal offences, including theft, unlawful excavation, illegal importation, illegal exportation, acquisition or placing on the market of unlawfully trafficked cultural objects, falsification of documents, and destruction and damage. It regulates jurisdiction and sets out measures to strengthen the fight against the illicit trade, including those relating to due diligence, the monitoring of the (online) trade and international cooperation among law enforcement. Although, as of January 2026, only seven states have ratified the 2017 Nicosia Convention, more appear to be considering ratification.

The European Union (EU) also acted, most notably through the introduction of a general prohibition on the import of cultural goods that were illicitly exported from third countries into the Union customs territory, as outlined in Regulation (EU) 2019/880 on the Introduction and Import of Cultural Goods (EU Import Regulation 2019/880). ⁷⁸ While the entire import controls regime has only become operational from 28 June 2025, the general prohibition to import cultural goods that were ‘removed from the territory of the country in breach of the laws and regulations of the country where they were created or discovered’ has been in effect since 28 December 2020. The ‘lawful’ provenance of a cultural object should be documented by export licences or, under certain conditions (namely, if it had been in a third country for a minimum of five years), by documentation showing that the artefact had left its country of origin before 24 April 1972. ⁷⁹ Such regulations represent a major step in the fight against illicit trade because they involve a de facto shift in the burden of proof to holders of the artefact, as discussed next.

B. The Importance of Due Diligence Standards and Provenance Research

Since cultural objects often circulate without documentation of their provenance, it is challenging to establish exactly when, from where and from whom cultural objects were taken. ⁸⁰ In this context, reversing the burden of proof through the introduction of (mandatory) due diligence standards is crucial to efforts to identify and recover looted artefacts.

As an ethical standard, the obligation to actively research the provenance of artefacts prior to acquisition has been included in the ICOM Code of Ethics for Museums since the 1980s. ⁸¹ As a legal standard, it was first introduced in the 1995 UNIDROIT Convention:

In determining whether the possessor exercised due diligence, regard shall be had to all the circumstances of the acquisition, including the character of the parties, the price paid, whether the possessor consulted any reasonably accessible register of stolen cultural objects, and any other relevant information and documentation which it could reasonably have obtained, and whether the possessor consulted accessible agencies or took any other step that a reasonable person would have taken in the circumstances. ⁸²

Within the (private-law) framework of the 1995 UNIDROIT Convention, however, due diligence standards come into play only when a claim arises and it is established that the artefact was stolen or unlawfully exported, in order to determine whether the new possessor is eligible for compensation for the value of the stolen or looted object. Only a new possessor who ‘neither knew nor ought reasonably to have known’ of the unlawful provenance of an artefact may claim compensation. ⁸³

Meanwhile, this standard has gained importance in its own right. It has been replicated in other legislations and has entered into the national legislations of countries that did not accede to the 1995 UNIDROIT Convention. ⁸⁴ In addition, requirements regarding provenance research have appeared in immunity for seizure regulations. Under the UK Tribunals, Courts and Enforcement Act 2007 (as amended in 2008), for instance, the provenance of an artefact must be researched and documented in order to ensure that artefacts on an international loan to the UK will be immune from seizure. ⁸⁵

The adoption of the 2017 UN Security Council Resolution 2347, exclusively dedicated to cultural heritage protection, gave an important boost to mandatory due diligence standards as part of import or trade prohibitions. ⁸⁶ It requests states to take steps to prevent and counter illicit trafficking, ‘including by prohibiting cross-border trade in such illicit items … which lack clearly documented and certified provenance, to allow for their eventual safe return’. ⁸⁷ It also urges states to adopt measures to engage ‘museums, relevant business associations and antiquities market participants on standards of provenance documentation, differentiated due diligence, and all measures to prevent the trade of stolen or illegally traded cultural property’. ⁸⁸ The UN General Assembly, in 2021, reinforced this by urging states to

take appropriate measures to ensure that … all actors involved in the trade of cultural property…, are required to provide verifiable documentation of provenance as well as export certificates, as applicable, related to any cultural property imported, exported or offered for sale, including through the Internet. ⁸⁹

The 2017 Nicosia Convention – taking a criminal-law approach – indeed provides for such mandatory standards: state parties should take measures to ensure that the acquisition or ‘placing on the market’ of stolen or unlawfully transferred cultural property is a criminal offence, not only if the person knowingly acquires such objects but ‘also in the case of a person who should have known of the cultural property's unlawful provenance if he or she had exercised due care’. ⁹⁰ In a similar vein, the EU Import Regulation 2019/880 relies on documentation to support the lawful provenance of cultural objects and requires importers to provide

documents and information providing evidence that the cultural goods in question have been exported from the country where they were created or discovered in accordance with the laws and regulations of that country or providing evidence of the absence of such laws and regulations at the time they were taken out of its territory. ⁹¹

Due diligence in terms of mandatory provenance research, in other words, is gradually transforming from an ethical standard or criterion for eligibility for compensation upon restitution (as in the 1995 UNIDROIT Convention) into a legal obligation sanctioned under criminal law for the demand side of the chain. In a sector that is renowned for its lack of transparency and that has traditionally focused on the authenticity of cultural objects and less so on legal in terms of provenance, this may well be a game changer; including because knowledge about the provenance of cultural objects will enable original owners and source communities to reconnect with their lost cultural heritage.

VII. Conclusion

The developments discussed in this contribution confirm that the legal framework governing cross-border restitution of cultural objects is rapidly evolving. While fragmentation remains characteristic of the field, the analysis has shown that this fragmentation reflects the coexistence of distinct legal approaches.

In the traditional ownership approach (Section III), cultural objects are treated principally as items of property, meaning that private-law rules on good-faith acquisition and limitation periods may make claims inadmissible, resulting in the paradox of lawful possession of unlawfully removed cultural objects. The ethical approach (Section IV) seeks to mitigate this paradox through non-binding soft-law instruments calling for equitable solutions and recognition of the intangible value of cultural objects, as symbols of cultural identity or lost family history. The human rights approach (Section V) similarly places emphasis on cultural values and a continuing connection between objects and people, rather than on economic (exclusive) ownership rights. Finally, the criminal law approach (Section VI) strengthens the regulatory role of states by shifting the burden of proof to possessors and by targeting the demand side of the chain.

These divergent approaches demonstrate that cultural objects may be conceived as belonging to states, communities or private actors, depending on the nature of the object and on the legal approach one takes. The recent international declarations calling for restitution and return highlighted in the introduction – particularly the Qingdao Recommendations and the Brasília Declaration – largely adopt a state-centred approach in line with the 1970 UNESCO Convention treating national states as ‘right holders’, and place restitution and return at the heart of efforts to achieve redress for past injustices. This reparative dimension is of particular importance in light of the historical context in which many collections were formed. At the same time, these declarations resonate with the idea of cultural rights in their focus on non-state actors such as (Indigenous) communities as reflected in UNDRIP. Against this background, it seems essential to develop frameworks that focus on cooperation instead of on absolute ownership rights, in acknowledgement that, at times, there may be more than one ‘right holder’ in relation to the same object.

Last but not least, one development stands out: the growing importance of provenance research and (mandatory) due diligence standards. Provenance research increasingly shapes the field and has moved from an ethical standard to a legal obligation. Its significance, however, extends beyond determining legitimate ownership. Provenance research also enables source communities to identify and reconnect with their lost heritage and allows museums to present contextualised narratives of the objects they hold. In this way, debates over restitution are also debates about reconnection, representation and the stories that cultural institutions tell about the past. Taken together, these developments point to a broader reorientation in the field in which cultural objects are increasingly valued for their heritage value to the people with whom they are connected.