Historically, criminal offenses were proved through witness testimony, physical evidence, confessions, and rudimentary forensic techniques such as fingerprinting. But with the dawn of the digital era, prosecutors have increasingly relied on evidence gleaned from the modern arsenal of consumer technologies, such as cell phones or automated systems. Although much has been written about prosecutors’ use of such evidence to prove a defendant’s guilt, far less attention has been given to the challenges faced by the defense in accessing, presenting, or attacking forms of proof derived from sophisticated consumer technologies. This chapter aims to fill that gap, first by presenting a taxonomy of digital proof and then by isolating the critical characteristics of such evidence. The chapter suggests that this taxonomy can support efforts to formalize and standardize a defendant’s ability to marshal defense evidence for exculpatory and adversarial purposes as readily as the government does to inculpate.