The Cassirer family from Munich have been embroiled in a legal battle with the Thyssen-Bornemisza Museum since 2006, when Claude Cassirer first discovered Camille Pissarro's 'Rue Saint Honoré in the Afternoon - Effect of Rain' was in the Spanish capital.
The painting, currently valued at €13 million ($16.5 million), was allegedly taken from Claude’s grandmother by Nazis who forced her to sell it to them for a nominal price in 1939.
It eventually came to be owned by Baron Thyssen, who first put it on display in his museum in 1992.
In 2012, a California court rejected the Cassirers’ claims that the painting should be returned to them by the Thyssen Foundation.
But even after Claude’s death, the Cassirers has continued to appeal and file new lawsuits against the Spanish art foundation, prompting Spain’s Ministry of Culture to veto every claim made by the wealthy Munich family.
“There’s no denying that the Spanish government has de facto control over the Thyssen Foundation and could return the painting if they wanted to,” Stuart Dunwood, the Cassirers’ lawyer, told Spanish national daily El Mundo.
Officials from Spain’s Ministry of Culture argue that Claude Cassirer’s grandmother Lilly already received 120,000 Deutsch Marks in compensation from the German government in 1958, thus giving up the painting's ownership rights.
According to the National Archives of the United States, around 20 percent of art in Europe was looted by the Nazis, with over 100,000 items that haven't yet been returned to their rightful owners.