So say art law specialists Pierre Valentin and Hannah Shield, who have published their analysis of the case in an article entitled Out of the shadows of the Third Reich.
To complicate matters further, the New York Times reports that as the 1938 law allowing the Nazis to confiscate artworks from museums has never been rescinded, those institutions from which around 380 works in the hoard were seized may have no claim on them either.
Cornelius Gurlitt, in whose apartment the works were found, is the son of art dealer Hildebrand Gurlitt, who allegedly acquired the 'degenerate' art at Hitler's request with a view to its disposal.
Although Gurlitt Junior, now 80, is under investigation for tax evasion in relation to the hoard, to date he has not been charged with any offence and he still lays claim to the art.
"The law of restitution is complex and claims can take a long time to resolve," Valentin and Shield write.
"Claimants will be expected to prove ownership and their right to pursue the claim as heirs of the original owner. A fundamental obstacle in their way could be the rules on limitation. Depending on the jurisdiction in which claimants bring their claims, they may find that the claims have expired, because too long a period of time has lapsed since their forebears lost possession of the artworks."
The complexity of rules across a number of jurisdictions means that the exact status of many of the 1400 works in the €1bn hoard remains unclear.
"If German rules of limitation apply, it may well be the case that any claim brought today would be out of time because more than 30 years have passed since Gurlitt Jr came into possession of the artworks," say Valentin and Shield.
"Whether courts outside Germany have jurisdiction over claims to the artworks, and whether such courts would apply limitation rules more favourable to the claimants, will depend on the facts in each case."
However, international precedent means that politics may eventually intervene in the law, they add.
"The German government may also decide to intervene because the circumstances are such that applying the law would be so iniquitous as to shock the collective conscience."