This chapter explores the legal and ethical implications of using artificial intelligence (AI) in the criminal justice system. It presents various perspectives on how AI is being used in different stages of the criminal justice process, such as in policing, court proceedings, and sentencing. The chapter discusses concerns regarding the interpretability and potential biases of the machine learning algorithms used in these applications. It also examines governance mechanisms proposed by the EU Commission, the performance of sentencing algorithms, and ethical considerations surrounding the use of AI in the justice system.