Preventive custody and presumption of innocence in a Justinian constitution (C.I. 9.4.6). The essay discusses the connection of the Justinian discipline on maximum terms of preventive custody (C.I. 9.4.6) with the so-called principle of presumption of innocence. This principle, known to the Romans, continues to operate in late antique law as ‘rule of treatment’ and ‘rule of judgement’. The paper outlines the legal framework of the Justinian Age through a combined examination of C.I. 9.4.6 with other provisions collected in the Theodosian and Justinian Codes and with jurisprudential texts. In evaluating the link mentioned above, we must avoid modernizing suggestions, which obscure the distance between modern and Justinian representations of the defendant's guarantees.