Harry Bout and his support requested a commutation so that he can be transported to his home country of The Netherlands several times, in 2010, and again in 2018 (that was the 4th time such a request was made). The next time Harry can file a request for commutation of his sentence is in 2020.
Here are a few of the documents in support of a commutation:


Dutch political party D’66 letter to The Honorable Jennifer Granholm
Humanity for Prisoners letter in support of a commutation or pardon for Harry Bout (7/8/2010)
Epafras Foundation support letter for commutation Harry Bout-2007