In response to the growing overdose crisis, many prosecutors are treating overdose deaths as homicides. Since 2010, prosecutions for drug-induced homicide (also known as drug delivery resulting in death) have increased at least threefold. Criminal defense attorneys and defendants' families have asked for assistance in understanding these cases and how to defend them. This Toolkit is an effort to provide that help. This 2021 edition of the Toolkit now includes recent favorable caselaw and links to the amicus curiae briefs filed by the Action Lab and its partners that were successful in those cases; an expanded section on racial disparities and person-first representation; more material and case law in several of the states that are most aggressive in pursuing DIH enforcement; a brief section on ineffective; and information regarding forthcoming DIH research conducted by the Action Lab.