When intimate partner violence occurs, both victims and perpetrators may justify the violence. However, efforts to understand justifying violence typically rely on written descriptions of violent acts or are assessed well after the violence has occurred. Do victims and perpetrators justify violence even while they see it happening? A novel paradigm addressed this question in two cross-sectional studies (Study 1, N = 535 and Study 2, N = 480). Using this paradigm, participants in the violent and non-violent relationships gave in-the-moment and continuous justification ratings (using a slider) as they watched video clip(s), each depicting a couple having a heated and violent fight. The results showed that participants who previously had experienced victimization or perpetration were more likely to justify the violence, both during and after watching the violent clips. This research provides new insights into the nature of violence justification and offers a novel paradigm for future studies.