The integration of artificial intelligence (AI) into the criminal justice system offers transformative opportunities to enhance efficiency, accuracy, and fairness in law enforcement and legal processes. However, it also presents significant risks, including potential biases, lack of transparency, and privacy concerns. This chapter examines the dual-edged nature of AI applications in the criminal justice system through the regulatory framework of the European Union’s AI Act. By analysing these regulatory measures, this chapter highlights how the AI Act seeks to mitigate the inherent risks of AI while fostering its potential to improve justice outcomes. This exploration underscores the necessity of continuous monitoring and adaptive regulation to balance innovation with the protection of fundamental rights, ensuring that AI contributes positively to the criminal justice system. Furthermore, it delves into case studies in which AI has both succeeded and failed within the legal framework, offering insights into best practices and areas requiring caution. The chapter also discusses the ethical implications of AI in policing and judicial decisions, emphasising the importance of developing AI systems that are not only technically robust but also ethically sound.