PROJECT SUMMARY Through the research and training described in this K01 proposal, the P.I. (Dr. El-Sabawi) will acquire the necessary skills to become an independent researcher who uses legal epidemiological methods to study and design evidence-based laws and policies that improve the health of persons who use drugs (PWUD). Overdose deaths are surging across the U.S., with 40 states reporting increases in mortalities for the 12 month period ending in May 2022. Some prosecutors have responded to local overdose crises by charging persons who distribute drugs that cause an overdose death with homicide (drug-induced homicide) (DIH), resulting in dramatic increases in DIH prosecutions since 2011. Prior research has demonstrated that increased police activity and enforcement of criminal laws are largely ineffective in decreasing drug use and often lead to poorer public health outcomes for PWUD. However, the effects of the prosecutorial implementation of DIH laws on public health remains largely unstudied —equally as unstudied is the relationship between prosecutorial actors and the local public health and treatment infrastructure. With this 5-year K01, the P.I. aims to examine the prosecutor’s role in addressing the overdose crisis by focusing on how policy implementation decision-making is affected by socio-ecological (S.E.) factors, including the presence of other organizations (public health departments and treatment infrastructure); organizational relationships between the criminal legal, public health, and treatment systems; and the perceived effect of such prosecutions on drug use and treatment- seeking behaviors. The P.I. will conduct exploratory semi-structured interviews of prosecutors (AIM 1), local public health administrators, members of local management entities, defense attorneys, and PWUD (AIM 2) in North Carolina to capture the S.E. factors present in localities where prosecutors have chosen to pursue DIH cases versus the factors present in localities where prosecutors have chosen not to pursue such charges. Using the data gathered in AIMs 1 & 2, the P.I. will develop a Socio-Ecological Model (SEM) of policy implementation explaining how S.E. factors (including public health and treatment infrastructure) influence the implementation of DIH laws and how such implementation is perceived to influence the behaviors and experiences of PWUD (AIM 3). The P.I. will work with an accomplished, multidisciplinary mentorship team (Dr. Taxman, Dr. Rudes, and Prof. Beletsky) to master four relevant areas of training: (1) policy implementation science, (2) advanced legal epidemiological evaluation, (3) qualitative interviewing, and (4) implementation study design. In doing so, this K01 award advances the development of the P.I. as an independent and productive researcher. The research presented in this K01 award addresses an important public health concern and has the potential to advance the field by developing a SEM that posits how criminal legal ac...