The decision allows Hicks to keep $100,000 Australian ($102,300 U.S.), Adelaide Now reported. Random House, which published "Guantanamo: My Journey," reports the book has sold about 30,000 copies.
Hicks, an Australian convert to Islam, was captured in Afghanistan in 2001 and sent to the U.S. detention center at Guantanamo, Cuba, where he was classified as an enemy combatant. In 2007, he pleaded guilty to providing material aid to terrorists, receiving a five-year sentence with all but nine months suspended.
He was allowed to serve his sentence in Australia.
The director of public prosecutions, who last year obtained a court-ordered freeze on Hicks' royalties, said statements Hicks made when he pleaded guilty cannot be considered reliable for purposes of the Australian Proceeds of Crime Act.
"I feel that this has cleared my name," Hicks said. "I feel like this acknowledges Guantanamo Bay and everything is illegal."
Hicks says he was tortured during his years in Guantanamo.
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