Prescription drug monitoring programs — a technology originally designed for law enforcement — have been used by health care systems to combat the opioid crisis since the early 2000s. In her new book “Policing Patients,” St. Louis University Associate Professor Liz Chiarello speaks to the technology’s effects on overdose rates and patient outcomes. She also sheds light on the tool’s effect on doctors, pharmacists, and law enforcement; and what this has meant for patient care.