A new study found that drug decriminalization in Oregon did not cause an increase in overdose mortality in the state—refuting a narrative often pushed by opponents of decriminalization.
By tracking the influx of fentanyl into Oregon’s unregulated drug market, the authors of the study—which was published September 5 in the Journal of the American Medical Association (JAMA)—were able to account for the increase in overdose deaths that coincided with the adoption of Measure 110.
“I think this study has a role in the post-mortem for Measure 110,” Michael Zoorob, the study lead and a consultant at Rhode Island Hospital, told Filter. “A lot of people wrongly attribute the increase in overdose death rates that occurred in Oregon in recent years to Measure 110, but that’s not consistent with the evidence.”
Oregon voters approved Measure 110 in 2020. It decriminalized the possession of small amounts of all banned drugs, and greatly boosted funding for treatment, harm reduction and other social supports. It took effect on February 1, 2021, and was the first measure of its kind in the United States.
On March 1, 2024, following public and political backlash, Oregon legislators approved House Bill 4002, which recriminalized drug possession. That took effect on September 1, making low-level possession a misdemeanor punishable by up to 180 days in jail.
A press release from the Drug Policy Alliance called HB 4002 “a return to the failed approach of law and enforcement and the criminal legal system as the primary response to people struggling with substance use disorders, instead of health and service providers.”
The JAMA study demonstrated what Dr. Zoorob said may already seem “obvious” to many advocates: A shifting drug supply, principally the growing prevalence of fentanyl, drove the increase in Oregon’s overdose deaths in the relevant period.
In contrast, the authors concluded, “no association between M110 and fatal overdose rates was observed.”
This was the first study to examine the circumstances around Measure 110 in this way.
“In a lot of studies, we do account for the arrival of fentanyl when we are speaking with participants in smaller-scale qualitative studies,” Saba Rouhani, assistant professor of epidemiology at the NYU School of Global Public Health, told Filter. “But we haven’t been systematically accounting for the fact that fentanyl hit these different states at different times.”
Dr. Rouhani, who was not involved in the new study, said that its methodology was highly rigorous. “They adopted one core technique and replicated it with four different causal inference models; they were even able to replicate the findings of contradictory studies that have come out.”
The research group used drug seizure data from the National Forensic Laboratory Information System to first model the spread of fentanyl across the US geographically. “The first finding is the East to West pattern that people have talked about,” Zoorob said.
“The change point in Oregon where we see fentanyl enter the market is roughly the same as when Measure 110 takes effect.”
The group used a statistical procedure called change point analysis, which looks at the point in time that you see a dramatic change in the level of a variable, in this case, fentanyl in the drug supply.
“The change point in Oregon where we see fentanyl enter the market is roughly the same as when Measure 110 takes effect,” Zoorob said. A chart in the study illustrates how, by the time Oregon reached this point in early 2021, more than 40 other states had previously done so.
Next, the researchers used a regression model to quantify how much of the changes in drug overdose death rates between states over time were attributable to fentanyl exposure. “We show that fentanyl exposure explains more than half of that variation, which is crazy,” Zoorob said.
Third, Zoorob’s team was able to replicate the findings of an earlier study, published in the Journal of Health Economics, which had found that decriminalization accounted for a 23 per cent increase in overdose deaths in the state.
When they controlled for fentanyl, the effect of decriminalization was nullified.
“If you ignore the transition of the drug supply, we find a statistically significant effect with Measure 110 contributing to overdose,” Zoorob explained. “But what’s really happening here is that there’s this confounding variable: fentanyl exposure. If we adjust for that, the effect of Measure 110, or drug decriminalization, shrinks to zero.”
A recent Drug Policy Alliance report states that decriminalization in Oregon was designed to reduce the harms of drug criminalization, and that under Measure 110 there was substantial progress toward this goal. Advocates didn’t claim that decriminalization in itself, as opposed to legal regulation, would make the drug supply much safer.
Under Measure 110, the state saw a reduction in drug possession-related arrests and pumped hundreds of millions of dollars into treatment. The report notes that decriminalization also saved Oregon nearly $40 million in criminal-legal system costs and caused a significant increase in the number of people accessing substance use disorder treatment and other services.
However, a state audit released January 2023 was critical of Measure 110, flagging a number of deficiencies in its implementation. One issue it highlighted was that the citizens’ panel overseeing new treatment funding was slow in delivering the money, and the health authority had not provided the panel with adequate support.
“The fact that the money and resources to really focus on health outcomes came later didn’t do the public impression of this policy any favors.”
Lawmakers also declined to fund the $50,000 police training intended to smooth the new ticketing system designed to get people into treatment—an issue that would later be flagged in several other reports, though many advocates have said the involvement of law enforcement was unlikely to encourage people to feel safe in accessing treatment.
“The policy was actually a two part policy,” as Rouhani noted of Measure 110’s decriminalization and funding elements. “The second part took longer to implement. The fact that the money and resources to really focus on improving health outcomes came later didn’t do the public impression of this policy any favors.”
The majority of the funds to expand services were not disbursed by the Oregon Health Authority until after August 2022, 18 months after the law took effect.
Proponents of decriminalization have accused Oregon’s politicians of scapegoating widespread public issues on Measure 110, further harming public perception of the law.
As noted in the Drug Policy Alliance report, external factors like increased evictions and homelessness—in part due to COVID-19 eviction protections lifting in June 2021, and increased economic insecurity during the pandemic—all exacerbated Oregon’s housing crisis. From 2020 to 2022, the report notes, the state’s unhoused population grew by 23 percent.
“Recriminalization went through,” Rouhani said, “but I think it’s important for the historical record to be really rigorous in how we evaluate and reflect on what happened with this policy.”
Rouhani believes that we aren’t likely to see—nor be able to measure—the positive health outcomes from policy changes like decriminalization until they are in effect longer-term.
“Given that these policies are now being repealed, it really limits our ability to see the impacts that decriminalization could have on fostering supportive trajectories of care for people who use drugs,” she said. “But we know that arresting people who use drugs is largely ineffective at deterring future use or crime, and increases risks of a cascade of negative health outcomes.”
Criminalization and arrests are associated with a higher risk of overdose, create barriers to employment and housing, and disproportionately impact people of color and other marginalized populations. “We would expect that [removing criminalization] would in turn, translate to positive health outcomes longer-term,” Rouhani said.
When it comes to future research, Rouhani said that Zoorob’s study can not only shed light on what happened with Measure 110, but also has implications for how researchers do “outcomes research writ large” in the context of such a volatile drug market.
“If it happens to coincide with changes in drug supply, people will potentially misattribute changes in public health outcomes to a certain policy.”
Zoorob feels it is beyond the scope of this paper to suggest whether or not other states should take up decriminalization. But he said that he hopes it can help with the analysis of other drug policy decisions, and that he would like to see more studies of individual health outcomes amid drug policy reforms.
“I think we need to have some humility about how much we can learn from one intervention in a single state over a short period of time, or from a single study,” Zoorob added.
“But the key takeaway is that Measure 110 did not cause this increase in overdose deaths,” he emphasized of his latest research. “We’re likely going to have this problem whenever we debate public policy. If it happens to coincide with changes in drug supply, people will potentially misattribute changes in public health outcomes to a certain policy, when really it comes down to these broader macro issues.”
Photograph (cropped) by Neon Tommy via Flickr/Creative Commons 2.0
The Influence Foundation, which operates Filter, previously received a restricted grant from the Drug Policy Alliance. Filter‘s Editorial Independence Policy applies.