19. At the Appeal Hearing, the Prosecution further argued that, given the extraordinary circumstances of the trial, during which two crucial witnesses did not testify due to intimidation, the Trial Chamber was obliged under Article 20(1) of the Statute to consider, proprio motu, receiving their written statements under Rule 89(F) of the Rules.[1] The Appeals Chamber recalls that, unless specifically authorised by the Appeals Chamber, parties should not raise new arguments during an appeal hearing that are not contained in their written briefs.[2] Given that the Prosecution raised this argument for the first time during the Appeal Hearing without authorisation from the Appeals Chamber, the Appeals Chamber declines to consider it.