Increase in Overdose Deaths Unrelated to Decriminalization of Possession

"Our findings suggest that the increase in the state’s fatal drug overdose rate after implementation of M110 should not be attributed to drug decriminalization, and the state’s contemporaneous transition to a fentanyl-based unregulated drug market is the more plausible explanation. We also observed that the contemporaneous recriminalization of drug possession in Washington coincided with increased drug overdose deaths. These findings are consistent with a 2021 qualitative study in which people who used drugs in Oregon reported that fentanyl had recently dominated the state’s unregulated opioid supply, increasing their risk of overdose.32

"Despite hopes that the implementation of M110 would lead to a decrease in overdose mortality, deaths increased substantially. It is worth noting that M110 had 2 components: (1) decriminalization and (2) substantial expansion of substance use disorder treatment, recovery, housing, and harm reduction services. Because the majority of the funds to expand these services were not disbursed by the Oregon Health Authority until after August 202211 (18 months after the law took effect), analyses that rely primarily on data between February 1, 2021, and August 31, 2022, only assess the decriminalization component of M110. Moreover, more than 50 years of drug criminalization has likely had persistent effects on behaviors relevant to overdose mortality, such as hesitation to call 911 to report overdose events,33-35 and acknowledging a highly stigmatized criminal behavior when seeking treatment.36,37 We do not know how long it would take for these attitudes and behaviors to change. Regardless, our analysis of Washington State suggests that recriminalization in Oregon may not reduce the rate of overdoses observed in a state saturated with fentanyl.

"Analyses of interventions intended to reduce overdose mortality or the consequences of criminalization, ranging from increased naloxone distribution38 to relaxed state marijuana laws,39 have similarly relied on models that did not account for the spread of fentanyl across the US. Such studies potentially misattribute the consequences of increased fentanyl exposure to the effects of public policies, or they conversely misattribute success to policies because control groups experienced fentanyl supply shocks during the study period. Synthetic control methods and similar causal inference models rely on assumptions of strict exogeneity that are violated when unincorporated time-varying factors (eg, fentanyl spread) are correlated with an exposure (eg, policy adoption) and an outcome of interest (eg, overdose rates).40,41 Because shocks to the drug supply drive changes in overdose and affect regions at different times,21,26 neglecting this dynamic is a threat to causal inference."