Part 4 Mutual Assistance through the Execution of Decisions and Orders of the Court
§ 41 Enforcement of Prison Sentences
(relating to Article 77 para. 1,Article 103 para. 1 and 2, and Articles 105, 106, and 110 of the Rome Statute)
(2) The prison sentence shall be enforced to the extent set forth by the Court. The provisions of the Criminal Code (Strafgesetzbuch) regarding suspension of enforcement of the remainder of a set period or a life-long prison sentence (§§ 57-57b of the Criminal Code) and the Criminal Procedure Code regarding enforcement of a prison sentence are inapplicable. The enforcement shall end when the Court so notifies.
Non-modification of sentence by State
EDIT.