the answer to that depends on your take of the letter Tohme wrote and signed "gifting" all rights on the artwork to BLS. Do you think it was legit and done with MJ's knowledge and blessing? If yes than the transfer is legal.
If you ask me, it is quite questionable. BLS and MJ hadn't seen each other since mid 90s. They allegedly reconnect in 2008. In this time Tohme writes and signs a letter gifting BLS the artwork and all rights. The letter doesn't have MJ's signature or initials on it. Tohme has at least one other example of abusing his power of attorney (Julien's auction that Tohme signed and Michael later fought to cancel). There is also the Hawk connection. Hawk is a lawyer that has a office where BLS has his studio. Hawk was a lawyer for Tohme. He also represented BLS during copyright transfer registration. Oddly enough even though the alleged "gifting" happened in 2008/2009 BLS didn't register for copyright transfer until 2010. BLS tried to sell the art for $88 Million. Sale didn't happen because Estate wouldn't give a release , reportedly Tohme was asked to authenticate his "gifting" letter but he refused to do so. Then BLS donated some of MJ's art to a children's hospital. Which seemed like a nice gesture but it turned out it wasn't MJ's original art, It was just replicas/ prints being donated. Now the book is being released by Wiesner in Germany. Wiesner is another person who had legal issues with MJ and his Estate.
So you tell me. Which is more likely to be true?
