The Washington Post previews the Prague conference and shares more stories of the knotty nature of restitution cases:

Government officials from around 49 countries, dozens of non-governmental groups and Jewish representatives will meet in Prague this week to review current practices. They are likely to sign a new agreement to step up restitution efforts. Some participants hope the conference will lead to the creation of a central body responsible for publishing updates on countries’ progress, which could prompt them to do more.

The task of restituting Nazi-looted works is an epic one. The Nazis formed a bureaucracy devoted to looting and they plundered a total of 650,000 art and religious objects from Jews and other victims, the Jewish Claims Conference estimates. […]

Austria is considered among the leaders of art restitution efforts, putting its larger neighbor Germany to shame. The Alpine Republic in 1998 passed a law governing art restitution and has since returned over 10,000 artworks. […] Lawyers and experts say many countries have not enforced the principles and hope they will agree at the Prague conference on a transparent way to report on progress. One of the main obstacles to art restitution is the difficulty in tracing the provenance and proving the ownership. […] The unique nature of the Nazi regime also makes it difficult to legally define which art was looted or not.

“The Nazis were very inventive, and thought up lots of ways to expropriate someone of their belongings,” said Christoph Bazil, head of the Austria’s art restitution committee. […] Even when claimants are successful at proving their ownership of an artwork, they have often been unable to retrieve the work of art due to rigid export bans on cultural patrimony.

A Jewish American heiress won a court battle with Hungary in 2000 for the return of art looted by Nazis, including works by Cranach, Van Dyck and El Greco. But the outcome was a Pyrrhic victory, as the works were not allowed to leave the country.

Heirs Race to Find Nazi-Looted Art Before Time Runs Out (Washington Post)