Evidence created by computer programs dominates modern criminal trials. From DNA to fingerprints to facial recognition evidence, criminal courts are confronting a deluge of evidence that is generated by computer programs. In a worrying trend, a growing number of courts have insulated this evidence from adversarial testing by preventing defendants from accessing the source code that governs the computer programs. This Note argues that defendants are entitled to view, test, and critique the source code of computer programs that produce evidence offered at trial by the prosecution. To do so, this Note draws on three areas of law: the Confrontation Clause, the Due Process Clause, and Daubert and its progeny. While courts and commentators have grappled with specific computer programs in specific criminal contexts, this Note represents the first attempt to justify the systematic disclosure of source code by reference to the structural features of computer programs.