In March 1933 Presidential Order 6260 prevented the release of gold coins by the US mint. This included the 1933 Double Eagles made in January and February at the Philadelphia mint. However some had already left the mint and about ten are thought to exist. In 1944 two were put up for auction including one owned by King Farouk of Egypt. The King's coin was not returned to the Treasury and vanished until reappearing in the 1990's when it was again seized. ( see coins you cannot legally own)

UPDATE
The Farouk coin is to be auctioned off with half of the money going to the mint.
So its now Legal to own!!!!