Scientific and technological progress and the development of computer and cybersecurity science provide substantial evidence-collection possibilities in criminal proceedings. Law-enforcement authorities, courts, trial participants and expert witnesses should be aware of such possibilities. Expert witnesses should be required to provide information on whether given computer software used by a given expert witness as support for the preparation of opinions is covered by a licence and whether the software has been approved by the manufacturer, as the use of unapproved software might generate errors. The expert witness’s use of fake software disqualifies a given opinion, as has been proven in this gloss.