Derek Fincham has a good analysis of the recent decision in Iran v. Berend (mentioned earlier here):
"The dispute ultimately came down to which nation's law should apply to the dispute, France or Iran. Under Iranian law, the object would be returned, but under French law, the 30 year statute of limitations period had elapsed, and Berend would have clear title."
Because the work has been in Berend's Paris apartment since its purchase in 1974, the Court ruled that French law applied, leading Fincham to wonder "why Iran did not pursue its claims in 1974, when the object was first sold."