Book excerpt: American prosecutors are asked to play two roles within the criminal justice system: they are supposed to be ministers of justice whose only goals are to ensure fair trials—and they are also advocates of the government whose success rates are measured by how many convictions they get. Because of this second role, sometimes prosecutors suppress evidence in order to establish a defendant’s guilt and safeguard that conviction over time. In Prosecution Complex, Daniel S. Medwed shows how prosecutors are told to lock up criminals and protect the rights of defendants. This double role creates an institutional “prosecution complex” that animates how district attorneys’ offices treat potentially innocent defendants at all stages of the process—and that can cause prosecutors to aid in the conviction of the innocent. Ultimately, Prosecution Complex shows how, while most prosecutors aim to do justice, only some hit that target consistently.