Aside from increases in adult marijuana possession arrests in border counties, a new working paper from the National Bureau of Economic Research has found that state marijuana legalization has little effect on neighboring states.
In the paper, The Cross-Border Spillover Effects of Recreational Marijuana Legalization, professors Zhuang Hao and Benjamin Cowan from the School of Economic Sciences at Washington State University found that legalization “causes a sharp increase in marijuana possession arrests of border counties relative to non-border counties.”
“If a county shares a physical border with [a legalized] state,” the authors note, “it experiences an increase in marijuana possession arrests of roughly 30 percent.”
However, the study found that the increased arrests are almost entirely among adults.
“[Legalization] has no impact on juvenile marijuana possession arrests,” according to the data, which also shows that there is no “evidence that marijuana sale/manufacture arrests… of border counties are affected on net by [legalization].”
While the counties bordering a legalized state see an increase in adult arrests, the researchers found that the counties farther from the border experience a decline in adult possession arrests.
Impaired driving statistics improved as well.
“DUI arrests decrease markedly for both border counties and non-border counties after [legalization],” the authors concluded.
The authors caution that the increase in border county arrests can’t necessarily be tied to increased trafficking of marijuana across state lines. Following legalization, “police officers might adopt new techniques or use more resources toward cracking down on what they perceive to be more illegal marijuana possession.”
The authors did not find an increase in employment of police officers in the bordering counties following marijuana legalization.
In conclusion, the authors suggest that marijuana legalization could cause an increase in law enforcement and criminal justice costs for the neighboring states.
Perhaps those states would be better served by joining their neighbors in legalizing marijuana for adult use, thus saving those law enforcement costs and earning tax revenue to boot.