Principles of provenance disputes

The claimant must first establish ownership, by producing titles, inheritances, inventories. The claimant must then show the circumstances of the loss: theft, spoliation, forced sale, confiscation, loss during a conflict. Proof may result from a body of indications where documents have disappeared.

The tribunal takes account of historical circumstances: victims of persecution have not always been able to keep or produce documents. The standards of proof are adapted.

A good-faith buyer is one who legitimately did not know of the defect in title. It is not enough to plead ignorance: the tribunal examines the diligence shown before the purchase. Checking databases, studying provenance, a consistent price, export documents: all are assessed with growing strictness.

For high-risk works (wartime, conflict regions), the diligence requirement is stronger. The absence of research could lead to loss of protection.

In some legal systems, the buyer becomes the owner after a period (acquisitive prescription). In others, the original owner may sue for a very long time. The tribunal applies the chosen law but may refuse to draw from it effects contrary to international public policy, notably in cases of spoliation.

Equity plays an important part in seeking a solution: sharing the value, restitution against compensation, long-term loan. The arbitrators may propose these solutions if the parties consent.

The 1998 Washington Principles and later declarations call for "just and fair" solutions for spoliated property. They are not binding, but they guide the arbitrators, who refer to them in assessing the circumstances of the spoliation and the buyer's diligence.

The 1970 UNESCO Convention and the 1995 UNIDROIT Convention also inspire the tribunal's reasoning, without applying directly between private persons unless incorporated by contractual reference or national law.