["Criminology &Public Policy, EarlyView. ", "\n\nResearch Summary\nTo estimate the effects of successive drug policy shifts on prosecutorial decisions, we employ a retrospective, longitudinal analysis of statewide aggregated charging trends (2008–2024). Focused on the changing landscape around possession of controlled substances (PCS), we examined the impact of three Oregon policies—Justice Reinvestment (2013), PCS drug defelonization (2017), and PCS drug decriminalization (2021)—on initial charge filings, charge bargaining, and charge dismissals and convictions. Across intervention periods, prosecutors filed a high percentage of PCS charges referred by law enforcement (average of 78.9%). Defelonization was associated with a significant drop in felony PCS charges, coupled with a significant increase in misdemeanor PCS charges. Following defelonization, the number of possession‐related dispositions began to steadily decline, with a lower conviction rate. Decriminalization was associated with an immediate decline in both misdemeanor and felony PCS charges and fewer overall dispositions, which coincided with an increase in dismissals, whereas conviction rates remained relatively stable. Across intervention periods, PCS charges, if not dismissed, were likely to remain consistent through dispositions (>92.5%), demonstrating little charge bargaining/variation. Despite fluctuations in the number of PCS charges filed, of those not dismissed, there appears to be a concerted effort on prosecuting those charges.\n\n\nPolicy Implications\nWith the advent of drug courts, diversion programs, defelonization, and Oregon's most recent period of decriminalization, states are experimenting with shifting drug policies. Defelonization and decriminalization impacted prosecutorial charging practices, more so than Justice Reinvestment. Policy makers should note that defelonization had the expected impact on PCS charges, and prosecutors seamlessly adopted the new law by switching their focus to misdemeanor PCS charges. Decriminalization contributed to a shrinking of actions related to prosecutorial charging; the majority of PCS offenses were no longer criminal, resulting in significantly fewer PCS arrest referrals, thereby forcing a dearth of prosecutorial charges.\n\n"]