Research in criminal justice settings with justice-involved people is an ethically fraught activity. Although many of the ethical principles in non-justice contexts apply to criminal justice research, justice settings are vulnerable to particular ethical challenges. This bears scrutiny because the potential harms arising from poor research practices can be serious and long-lasting. In this chapter, we bring a contemporary lens to ongoing and newly emerging ethical issues including (a) navigating ethical approval in closed justice settings, (b) reducing pressure to participate in research in coercive environments, (c) ensuring informed consent and offering inclusive opportunities to justice-involved populations, and (d) making use of criminal justice administrative data in a manner that protects privacy. Drawing on two contemporary case studies on research in prison settings and ownership of research data, we explore the ways in which these ethical issues have specific contours and challenges for participants, researchers, and criminal justice organisations. We offer several practical strategies for mitigating some of the key risks in this challenging area. We argue that criminal justice researchers can navigate the obstacles presented by justice settings with robust planning and consultation processes, collaborative research design and methodologies, and strong engagement with ethical statements and guides.