Political speech offences as defined in the Spanish Penal Code have made criminal scholars particularly uncomfortable since online social networks became popular and the number of users convicted by Spanish courts has increased. In this context, both ethical criticisms about their criminalization and those about the possible perverse effects of the criminal sanction have intensified. This study empirically analyses, in a sample of four hundred people, the defiance effect that can occur in the field of speech offences on social networks. The results suggest that participants would challenge the criminal law if they were convinced of these ideas, would tend to reoffend if sentenced, and would support a demonstration for decriminalization.