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The Effect of Marijuana Legalization on Crime Rates

Kylie E. McCarthy

University of New Haven

Photo by Rob Warner on Unsplash

The legalization of marijuana for recreational and medicinal use has been a topic of debate within the political and criminal justice systems for many years. Marijuana existed long before there were any laws criminalizing it, estimated to be first used at least 5,000 years ago (Hudak, 2020). Formal use in medicine began in the mid-1800s (Bridgeman, & Abazia, 2017), but each passing year led to new drug restrictions and legislations criminalizing and taxing it. Campaigning for presidency in the late 1960s, a component of Richard Nixon’s political strategy was to target minorities in society, specifically black individuals (Hodge, 2021). Prior to his taking office in 1969, the Civil Rights movement (1954-1968) was in full force. During the movement, Nixon capitalized on the uneasiness of white American’s apprehension towards change, and he created a storyline that correlated the civil unrest and crime rate with “drug using” people of color (LoBianco, 2016). He further sought to instill fear around marijuana use, specifically as a gateway drug to more dangerous drugs, although current research yields mixed results on the gateway drug theory (Nöel & Wang, 2018).

Shortly after his presidency began, Nixon addressed the nation by discussing Congress’s Drug Abuse Prevention and Control program, later coined as the War on Drugs. In October of 1970, the Controlled Substances Act was announced, becoming effective in May of 1971 (Gabay, 2013). This act classified the schedules of drugs from one to five, with definitions of their abuse and addictiveness, and examples of where each drug fit. Marijuana was classified as a Schedule 1 drug, defined as being highly addictive and without accepted medical use. As more recent research indicates, marijuana cannot be chemically addictive, although it can be habit forming (Drug Abuse Centers, 2019). Cannabis is widely used in the medical system as a treatment for chronic pain, chemotherapy related nausea, and some neurological disorders (Bridgeman & Abazia, 2017). Because of this, many argue that the Schedule 1 classification is incorrect, as we know that the addictive properties are minimal compared to other drugs, and marijuana has been used in medicine for hundreds of years.


With current knowledge regarding the use and abuse of marijuana, 17 states and Washington, D.C., have legalized cannabis for recreational and medicinal use, with 19 additional states allowing medical use only (American Nonsmokers’ Rights Foundation, 2021). However, while 37 states and D.C. allow the use of marijuana in some capacity, there are many arguments against its value. Such arguments against its legalization include concern for potential increased risk of teen use, rising marijuana related medical issues, and the belief that legal access and greater use of marijuana will increase the level of crime. Regardless of the changes that have occurred pertaining to legalization status, there is still little understanding of marijuana use and how it influences many areas of life, including the law.


At this point in time, decisions on legalization are decided at the state level, but remain illegal under federal law (National Conference of State Legislatures, 2021). This paper focuses on this relationship between cannabis and criminality, by assessing existing research and three recent articles examining the relationship between marijuana legalization and crime, as well as the influence that opening medicinal dispensaries have on crime. Contemporary researchers hope to provide a more comprehensive understanding of marijuana use and how it impacts crime. With the steady increase in users across the nation (NIH, 2021), it is imperative that legalization status is guided by empirical evidence. At this time, limited and mixed results, combined with varied public opinion, create ambiguity. Further research should be conducted to assess marijuana use and legalization status, as marijuana use does not seem to be decreasing through legalization decisions.


Previous Research Findings

Being a relatively new area of study, there is not extensive research on marijuana legalization and its relation to crime rates. However, there is a vast amount of research on marijuana as a whole. While there are some inconsistencies in findings, the majority of research on marijuana’s effects on the brain indicate both short and long-term effects. One study suggested chronic users experience reduced hippocampal volume, resulting in weakened learning ability and memory, as well as reduced grey matter, which is responsible for controlled movement, memory, and emotions (Burggren et. al., 2019). Short-term effects of marijuana use can include reduced balance and motor control (Iversen, 2003). While there are detriments to using most drugs, marijuana also offers some benefits. In 2017, the National Academies of Science, Engineering, and Medicine published a thorough review of marijuana use in the medical field, revealing substantial support for cannabis as an effective treatment for individuals experiencing chronic pain, nausea caused by chemotherapy, and symptoms of multiple sclerosis (Therapeutic Benefits of Marijuana, 2017). In addition, marijuana has been used as a treatment for some mental disorders, including anxiety and post-traumatic stress disorder (Orsolini et. al., 2019).


In relation to marijuana and crime rates, there are many studies yielding mixed results, leading to vague understandings on the drug effects and crime. Some research has suggested a weak relationship between marijuana use and crime in chronic users. In a longitudinal study of 13 to 27-year-olds, Pedersen and Skardhamar (2010) examined consumption of cannabis and other substances from adolescence to early adulthood. They found a strong correlation between early use of cannabis and later involvement in crime, but noted a limitation to their research, in that substantial developmental and environmental changes occur during this time that also could account for involvement in crime.


Hughes and colleagues (2020) examined the relationship between medicinal and recreational dispensaries in Denver and neighborhood crime rates, comparing neighborhoods with dispensaries to those without. They found statistically significant support for an increase in violent offenses, including aggravated assault and robbery, but excluding murder. At the same time, there was significant support for the reduction of substance abuse offenses decreasing over time. This was suggested to be potentially related to increased use of marijuana, resulting in decreased use in other substances, such as alcohol, which has been shown to relate to increased violence in individuals with previous violent-prone behavior (Boles & Miotto, 2003).


On the other hand, there also has been support for the decrease in crime rates following recreational marijuana use and sales in Washington. Examination of reports from the FBI’s uniform crime report (UCR) revealed there was a drop in rape, property crimes, and theft across the state from 2010 to 2014, two years prior to and following legalization (Dragone et. al., 2018). The authors suggested various potential reasons for these drops, including the relaxed state one often feels while using marijuana, and the possible reduced role of criminal dealers that may resort to crime now that it could be purchased legally from a dispensary.


The highly mixed evidence surrounding marijuana use and crime contributes to inconsistencies in legalization across the nation. Some studies highlight its benefits and note reductions in crime, while others bring up concern for drug use and increasing crime rates. The mixed results leave policymakers with difficult decisions, trying to determine if they should follow the federal decision to keep marijuana illegal, or focus efforts on decriminalization and legalization. There are large amounts of support and opposition, with both sides advocating for what they believe will keep everyone the safest. To further assess this situation, three research teams were interested in examining how marijuana legalization influenced crime. The first sought to understand the spillover effect of legalization on crime in the bordering counties of Colorado and Washington. The second was interested in crime rates across those two states. And the third evaluated the opening of medicinal marijuana dispensaries in Washington, D. C.


Effects of Legalization in Colorado and Washington on Neighboring States

With the legalization of marijuana in Colorado and Washington in 2012, Wu and colleagues (2020) were interested in examining crime rates in the surrounding states, to analyze whether any changes occurred following legalization. Data from the FBI’s Uniform Crime Reports (UCR) was collected from 360 counties across Kansas, Nebraska, New Mexico, Oklahoma, Utah, and Wyoming, the states bordering Colorado. Data were also collected from 80 counties across Idaho and Oregon, which border Washington. Data ranged from 2003-2012 (pre legalization) to 2012-2016 (post legalization). This data provided information on serious violent and property crimes, categorized as Part I crimes, and less serious crimes that are categorized as Part II crimes. Using a quasi-experimental design, difference-in-differences analysis was employed to evaluate the spillover effect of crime in bordering and non-bordering counties. 


In the Colorado region, from 2003-2012 (pre legalization), the average number of property crimes per 100,000 residents was 2,364. Following legalization, from 2012 to 2016, property crimes decreased to an average of 2,034 per 100,000 residents. In the counties directly bordering the state of Colorado (i.e., counties located in Kansas, Nebraska, New Mexico, Oklahoma, Utah, and Wyoming), a larger decrease in property crimes occurred. Specifically, property crime cases located in bordering counties numbered 2,371 per 100,000 during pre-legalization and 1,723 per 100,000 during post legalization, an average decrease of 648 cases. In non-bordering counties, the decrease was smaller, declining from 2,363 cases per 100,000 during pre-legalization to 2,059 per 100,000 during post-legalization experiencing an average drop of 304 cases.


Although property crimes experienced the biggest drop in cases per 100,000 residents in Colorado, other crimes dropped pre and post legalization as well. In counties located in neighboring states that directly bordered Colorado, larceny reports dropped by an average of 519 cases per 100,000. In non-bordering counties, larceny reports dropped by 258 cases per 100,000. Additionally simple assault also experienced a decrease in both bordering and non-bordering counties. Prior to legalization, simple assault in bordering counties was reported 1,009 times per 100,000 and dropped to 827 cases, experiencing a drop of 182 cases per 100,000 residents. In non-bordering counties, a decrease in simple assault reports occurred by 86 cases per 100,000 residents. Finally, motor vehicle theft decreased by an average of 25 cases in bordering counties and 6 cases in non-bordering counties, per 100,000 residents.  


In the state of Washington, patterns of official crime reporting were similar, with a drop in most crimes following legalization. Violent crime in bordering counties dropped from 260 cases per 100,000 residents pre-legalization to 212 cases post-legalization, decreasing by an average of 48 cases. However, this drop was only significant in bordering counties, as non-bordering cases only dropped by three. Reports of aggravated assault in bordering counties dropped from 197 to 155, each per 100,000. However, non-bordering counties showed no increase or decrease, with an average of 144 cases both prior to and following the legalization of marijuana in Washington.


Overall, researchers reported there is some evidence to suggest that the legalization of marijuana did lead to a reduction in crime in neighboring states of Colorado and Washington. They specifically noted that property crimes, larceny and simple assault significantly decreased in counties located on the direct borders of the state. This was also seen in some Part II crimes as categorized by the FBIs UCR. Results suggest the potential for little consequences relating to crime following the legalization of marijuana.


Wu and colleagues (2020) were not the only researchers who were interested in the potential changes in crime following the legalization of marijuana in Colorado and Washington. Lu and associates (2021) utilized a quasi-experiment and multi-group interrupted time-series analysis to evaluate whether UCR data had changed following legalization in Colorado and Washington in 2012. To conduct this study, they conducted a monthly time series analysis of crime rates in Colorado and Washington and compared them to states that had not yet legalized marijuana. States considered in this study were Alabama, Georgia, Idaho, Indiana, Iowa, Kansas, Kentucky, Mississippi, Missouri, Nebraska, North Carolina, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia, Wisconsin and Wyoming.


Because examining the two states in a single group interrupted time series would have limited capability of verifying causality (i.e., marijuana legalization causing crime rate changes), these 21 states that had yet to legalize marijuana on a recreational or medical purpose on a large scale were employed as a control group and compared to Colorado and Washington to evaluate crime trend changes. Monthly data from 1999 to 2016 were obtained from the FBI’s UCR, measuring violent crimes (murder, manslaughter, aggravated assault, and rape) as well as theft, burglary, larceny, and robberies. The monthly crime rates per capita were calculated by the state’s population and multiplying by 100,000. Instead of evaluating changes in crime in Colorado and Washington to each control state, researchers used a multi-group approach to compare Colorado and Washington to the 21 control states altogether.


The results of this study suggested that overall, there were no long-term changes in crime rates in Colorado or Washington, when compared to the states that had yet to legalize marijuana. In terms of violent crime, there were no significant changes immediately following legalization. However, in Colorado, there was a statistically significant increase in property crime immediately following legalization, suggested to be due to an increase in larceny. In Washington, there was a statistically significant increase in property crime, burglary, and aggravated assault. All increases were suggested to be short-term. There were no long-term significant changes in crime following legalization in Colorado or Washington. However, there was a statistically significant reduction of burglary reports in Washington.


Lu et al. (2021) concluded that while there were some immediate or short-term crime rate increases at the point of legalization, there were no long-term shifts. The authors also noted that further research must be conducted to determine if the immediate effects of marijuana legalization could be influenced by the small-time frame between legalization and data analysis. In sum, the results indicated no long-term effects on crime rates following the legalization of marijuana in Colorado and Washington.


Effects of Medical Marijuana on Crime in Washington, DC

While marijuana was legalized for recreational use in some states, Washington, D.C., legalized marijuana for medical use (Altieri, 2013). Although declared legal for medicinal use in 1998, the first dispensaries in which an individual could purchase marijuana with proof of medical need were not opened until 2013, after the Barr amendment was overturned in 2011 (Zakrzewski et. al., 2020). Researchers were interested in examining the relationship between the opening of medical marijuana dispensaries and crime in D.C. at the micro-spatial unit. To examine this, researchers used intersections of five D.C. dispensaries to evaluate crime rates before and after they opened. Crime records from January 2008 to December of 2017 were obtained from available public data sets, including reports of homicides, assault with a deadly weapon, robbery, sexual abuse, burglary, motor vehicle theft, larceny, and arson (Zakrzewski et. al., 2020). Three of the dispensaries opened around the beginning of August 2013, with the other two opening in 2015. Statistical graphs were employed to examine changes in crime rates following dispensary openings.


Crime rates per year, prior to and following dispensaries being opened, were calculated. Results indicated the areas around the dispensary Capital Care had an average of 42 nonviolent crimes per year prior to the dispensary opening. Following this dispensary opening, there was an average of 39 nonviolent crimes per year. Three of the other dispensaries, National Holistic Healing Center, Herbal Alternatives, and Tacoma Wellness Center, showed no evidence of either violent or nonviolent crime increases following the opening of the dispensaries. However, the fifth dispensary, Metropolitan Wellness Center, experienced an increase in crime that was limited to robberies and larceny. However, Zakrzewski and colleagues (2020) noted both these crimes were increasing prior to the dispensary being opened, potentially influenced by an increase in nearby commercial properties opening.


It should be noted that because there was not a statistical test employed, the results of this study were not based on statistical significance. The authors cautioned that there was no causal evidence suggesting increasing crime rates following the openings of the five dispensaries. They suggested that the results of their study should be considered along with the research limitations, specifically that there were uncontrolled variables. Such variables include the opening of commercial stores that occurred around the same time as the opening of the Metropolitan Wellness Center, which could account for the subsequent increase in larceny and robbery. Therefore, there is not enough evidence to suggest that the opening of any of the five dispensaries was related causally to changes in crime rates, suggesting the need for future research to be conducted.


Discussion and Implications

This paper does not seek to support or reject the legalization of marijuana at the state or federal level, as changes in crime rates are only one relevant issue for legalization. Instead, it seeks to evaluate the claim often made by opponents of legalization, that this approach will increase crime in states and jurisdictions where legalization has occurred, and in states surrounding those areas. Overall, current studies reveal little evidence that marijuana legalization influences crime rates. Although marijuana may not become federally legalized in the foreseeable future, there were an estimated 48.2 million users nationwide in 2019 (CDC, 2021). Knowing this, adequate resources should be allocated toward research on the drug and its effects on society. Being the third most often used drug, behind alcohol and tobacco (CDC, 2021), users likely will continue, regardless of the drug’s legal status. Further funding towards research to gain a more comprehensive understanding of the drug is necessary to make evidence-based changes in legalization status.


The majority of studies at the present time evaluated the first states to legalize marijuana, since there is a greater amount of data on crime rates and marijuana use in these states. Future research should continue to evaluate states that recently have legalized marijuana, to determine if there is a difference in crime rates potentially linked to marijuana use in places other than Colorado, Washington, and Washington, D.C. All current studies were limited in various ways. Zakrzewski and colleagues (2020) noted that their research was focused on medicinal dispensaries, but recreational dispensaries could potentially yield different conclusions about crime. Wu and associates (2020) cautioned that their results could be influenced by societal or cultural aspects of neighboring states, which were not controlled for during their study. Finally, Lu and colleagues (2021) recognized their study should be replicated, in an effort to increase external validity and generalizability.



With the current research, it is suggested that legalization of marijuana and subsequent opening of dispensaries have little to no adverse effects on crime rates, specifically in the long-term. Wu and colleagues (2020) found that property crimes decreased following Colorado legalization in 2012. In Washington, property crime, larceny, and violent crime rates dropped, while aggravated assault saw no change. Lu and associates (2021) saw no long-term changes to crime rates within Colorado or Washington following legalization of marijuana. Although there was a statistically significant increase in property crimes in Colorado immediately following legalization, they were suggested to be driven by an increase in larceny that occurred prior to legalization. In Washington, there was a statistically significant increase in property crimes, burglary and aggravated assault, but only in the short-term. No long-term increases were reported. Finally, after examination of five medicinal dispensaries in Washington, D.C., Zakrzewski and colleagues (2020) reported no evidence of an increase in crime following the opening of four of them. One location experienced an increase in robberies and larceny, but the authors noted this change was initiated prior to its opening and may have been influenced by expansion of nearby commercial properties.


Overall, there is little evidence at this time to support the claim that the legalization of marijuana will result in an increase in crime rates, particularly in the long-term. However, this is a relatively new area of research, and the focus of legalization should surround empirical evidence with sound research designs to ensure that limitations in studies do not provide insufficient data for this claim. Only a few states have been examined empirically, and with legalization on the rise, it is pertinent to continue evaluating its effects on crime, as well as other concerns regarding marijuana use and legalization.


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Boles, S. M., & Miotto, K. (2003). Substance abuse and violence: A review of the literature. Aggression and Violent Behavior, 8(2), 155-174

Bridgeman, M. B., & Abazia, D. T. (2017). Medicinal cannabis: History, pharmacology, and implications for the acute care setting. Pharmacy & Therapeutics, 42(3), 180-188.

Burggren, A. C., Shirazi, A., Ginder, N., and London, E. D. (2019). Cannabis effects on brain structure, function, and cognition: Considerations for medical uses of cannabis and its derivatives. The American Journal of Drug and Alcohol Abuse, 45(6), 562-579.

Center for Disease Control and Prevention. (2021). Data and statistics.

Dragone, D., Prarolo, G., Paolo, V., & Zanella, G. (2019). Crime and the legalization of recreational marijuana. Journal of Economic Behavior & Organization, 159(1), 488-501.

Drug Abuse Centers (2019). Is marijuana addictive? Physically and or psychologically? American Addiction Centers.

Gabay, M. (2013). The federal controlled substances act: Schedules and pharmacy registration. Hospital Pharmacy, 48(1), 473-474.

Hodge, J. (2021). Fifty years ago today, President Nixon declared the war on drugs. Vera Institute of Justice.

Hudak, J. (2020). Marijuana: A short history. Bookings Institution Press.

Hughes, L. A., Schaible, L. M., and Jimmerson, K. (2020). Marijuana dispensaries and neighborhood crime and disorder in Denver, Colorado. Justice Quarterly, 37(3), 461-485.

Iversen, L. (2003). Cannabis and the brain. Brain: A Journal of Neurology, 126(1), 1252-1270

LoBianco, T. (2016). Report: Aide says Nixon’s war on drugs targeted blacks, hippies. CNN.

Lu, R., Willits, D., Stohr, M. K., Makin, D., Snyder, J., Lovrich, N., Meize, M., Stanton, D., Wu, G., & Hemmens, C. (2021) The Cannabis Effect on Crime: Time-Series Analysis of Crime in Colorado and Washington State. Justice Quarterly, 38(4), 565-595.

American Nonsmokers’ Rights Foundation (2021). Marijuana States Legal Map.

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Noel, W., & Wang, J. (2018). Is cannabis a gateway drug? Key findings and literature review.             National Institute of Justice.

Orsolini, L., Chiappini, S., Volpe, U., De Beradis, D., Latini, R., Papanti, G. D., Corkery, J. M. (2019). Use of medicinal cannabis and synthetic cannabinoids in post-traumatic stress disorder (PTSD): A systematic review. Medicina, 55(9), 1-14.

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Wu, G., Boateng, F. D., & Xiaodong, L. (2020). The spillover effect of recreational marijuana legalization on crime: Evidence from neighboring states of Colorado and Washington state. Journal of Drug Issues, 50(4), 392-409.

Zakrzewski, W. J., Wheeler, A. P., & Thompson, A. J. (2020). Cannabis in the capital: Exploring the spatial association between medical marijuana dispensaries and crime. Journal of Crime & Justice, 43(1), 1-15.  


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