The constitutional court in Karlsruhe ruled in favour of the man, who was handed a life sentence for murdering two people on a yacht in 1982.
He was released from jail in 2002 and says he wants his family name to be distanced from his crime.
The ruling could force publications to restrict access to online archives.
The man was onboard the sailing ship Apollonia in the Caribbean when he shot and killed two people and severely injured another during a row.
A book and TV documentary were made about the case.
