DVDs can be copy protected by incorporating regions which contain unreadable or subversive data within the data area (42). For example, such a region may be configured as a cell of a video object (VOB) (50) within a VOB file (51). Access to the region of subversive data is prevented during normal playback, for example, by ensuring that there are no pointers leading to the subversive region. To defeat such a copy protection method, the content on the copy protected optical disc is accessed by utilising the navigation provided for normal playback of the disc. Thus, the subversive regions are navigated around during copying of the disc. The accessed content is stored in a corresponding data area and, where subversive regions are identified, arbitrary data is incorporated within regions of the copy data area which correspond to regions of unreadable or subversive data in the original data area.