Legalized sports betting linked to a rise in violent crimes and property theft

A new study published in the Journal of Sports Economics has found that the legalization of sports betting in the United States is associated with an increase in violent and property crimes. The research indicates that incidents of assault and theft rise during and after sporting events in states where betting is legal, particularly when the home team loses unexpectedly. These findings suggest that the financial stress and emotional volatility tied to gambling may exacerbate aggressive behaviors among sports fans.

The motivation behind this research stems from a major shift in the American legal landscape regarding gambling. In 2018, the Supreme Court overturned the Professional and Amateur Sports Protection Act (PASPA). This decision effectively ended the federal ban on sports betting and allowed individual states to legalize and regulate the practice. Prior to this ruling, legal sports wagering was largely confined to Nevada. Since 2018, dozens of states have moved to create legal markets for sports betting.

State governments often view legalization as a means to generate tax revenue and curb illegal black-market gambling. However, the social costs associated with this rapid expansion remain under-examined. Previous psychological research has established links between problem gambling and impulsive behavior, alcohol consumption, and aggression.

The authors of the new study sought to determine if these individual psychological risks translate into broader societal harms, specifically in the form of increased criminal activity. They investigated whether the introduction of legal betting markets changes the nature of fan behavior, turning sporting events into catalysts for violence and property crime.

“We began this research in 2022 after observing growing interest in sports betting among both industry practitioners and the academic community. At the time, most existing studies focused on marketing-related questions, such as how betting promotions and advertising influence consumer decisions,” said study author NAME, who conducted the research while an assistant professor at the University of Michigan.

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“However, we identified a gap in the literature regarding rigorous empirical evidence on whether sports betting causes harm to consumers and society more broadly. To address this gap, we collected relevant crime data and designed this study.”

“Our work was inspired by David Card and Gordon Dahl’s study examining the relationship between NFL game outcomes and domestic violence, which found that upset losses were associated with more domestic violence,” added Hua Gong, an assistant professor at Rice University.

“When individuals are allowed to bet on sports, game outcomes may matter even more. We are therefore interested in exploring whether legalized sports betting amplifies emotional responses to game results and, in turn, leads to more irrational behavior or potentially more crime among bettors.”

To investigate this relationship, the researchers utilized a difference-in-differences study design. This statistical method allows scientists to compare changes in outcomes over time between a group that is exposed to a treatment and a group that is not. In this context, the “treatment” was the legalization of sports betting. The researchers compared crime rates on game days versus non-game days. They also compared crime rates in states before and after they legalized betting, using states that had not yet legalized betting as a control group.

The study relied on data from the National Incident-Based Reporting System (NIBRS). This is a comprehensive database maintained by the FBI that compiles detailed crime statistics provided voluntarily by law enforcement agencies across the country.

The researchers collected incident-level data from 2017 to 2021. This timeframe covers the period immediately before and after the Supreme Court decision. It also encompasses the onset of the COVID-19 pandemic. The analysis focused on four specific types of crime: assault, destruction of property, larceny, and vehicle theft. These offenses were chosen because they are often associated with impulsive aggression and have been linked to sports events in prior literature.

The sports data included in the analysis covered games from the four major North American professional leagues. These are the National Football League (NFL), the National Basketball Association (NBA), Major League Baseball (MLB), and the National Hockey League (NHL).

The researchers gathered information on game schedules, locations, and final scores. They also obtained historical betting odds from Sportsbook Review. These odds were used to determine which teams were favored to win and by how much. This allowed the authors to identify games where the outcome was unexpected, such as when a heavily favored home team lost.

The sample was divided into two distinct periods due to the disruptions caused by the COVID-19 pandemic. The pre-pandemic sample included 1,641 games occurred between April 2017 and March 2020. The post-pandemic sample consisted of 772 games played between July 2020 and December 2021. The researchers focused specifically on crimes reported from the start of a game until four hours after it concluded. They compared these numbers to crime reports from the same time window on the day prior to the game.

The analysis revealed a statistically significant increase in crimes in states with legal sports betting markets. This uptick was observed during the window of time surrounding the games. The data showed that the legalization of betting led to a rise in total incidents, including assaults and larcenies. The effect was present for both home and away games but was notably stronger for home games.

The researchers found that the nature of the game’s outcome played a substantial role in the magnitude of the crime increase. The study highlights that aggression was most pronounced when the home team lost a game they were expected to win. In the pre-pandemic period, home games with such unexpected outcomes were associated with a roughly 93 percent increase in assaults compared to the baseline. This suggests that the frustration of losing a bet, compounded by the disappointment of a home team loss, acts as a powerful trigger for violence.

The study also identified “spillover effects” in regions adjacent to states with legal betting. Many metropolitan areas in the United States span across state lines. In cases where one state legalized betting while its neighbor did not, residents of the non-legal state might travel across the border to place wagers. The data showed increased crime rates in these neighboring border counties on game days. This implies that fans may be traveling to place bets and bringing their betting-induced aggression back to their home communities.

The researchers conducted further analysis to understand the mechanisms driving this aggression. They sought to distinguish between aggression caused by financial loss and aggression caused by general emotional stress. To do this, they categorized games based on their predictability. A loss in a “predictable” game implies a shock to the bettor who likely wagered on the favorite. A loss in an “unpredictable” game is a risk the bettor likely accepted in advance.

In the pre-pandemic period, the increase in crime was primarily driven by unexpected outcomes in predictable games. This points to financial loss as the main culprit. Bettors likely placed money on “safe” bets and reacted aggressively when those bets failed. However, the pattern shifted in the post-pandemic period.

After games resumed following the COVID-19 hiatus, the link between aggression and strictly financial indicators weakened slightly. Instead, the researchers found that “stressful” games—those with close scores or overtime finishes—contributed to higher crime rates regardless of whether the outcome was a massive upset.

This indicates that as the sports betting market matured, the general anxiety and emotional arousal associated with wagering became a significant driver of aggression. The excitement and stress of the gamble itself, alongside the potential for loss, appear to fuel hostile behavior.

“The main takeaway from our study is that the introduction of legal sports betting is associated with a significant increase in crime on game days, particularly assaults,” Wang told PsyPost. “We also find spillover effects in neighboring states where sports betting had not yet been legalized: areas with close proximity to major sports teams experienced similar increases in crime.”

“In addition, bettors initially tended to wager on more predictable games, with aggression typically arising from financial losses. Over time, however, they shifted toward more unpredictable contests. These games are more likely to generate heightened excitement and in-game stress, which can increase aggression even in the absence of financial losses.”

As with all research, there are some limitations to note. The analysis used local games as a proxy for periods of high betting activity. However, modern sports betting allows individuals to wager on games happening anywhere in the country or the world. This means the study likely underestimates the total impact of betting on crime, as it does not capture incidents related to betting on non-local games. The findings essentially represent a lower bound of the true effect.

Another limitation involves the geographic variation in the data. The specific states included in the pre-pandemic and post-pandemic samples differed based on when they legalized betting. This makes it difficult to perfectly compare the two time periods. It is possible that the observed shift in bettor behavior is partly due to differences in the populations of the states that legalized betting later.

Future research is needed to explore these dynamics in greater detail. The current study focused on regular season and playoff games for four major leagues. It did not analyze major standalone events like the Super Bowl or the NCAA “March Madness” basketball tournament. These events attract massive betting volumes and could generate different patterns of behavior.

Future studies could also examine the long-term trends to see if the novelty of betting wears off, potentially reducing aggression over time. Investigating specific geographic differences could also help policymakers tailor regulations to their specific communities.

The study, “The Impact of Legalized Sports Betting on Aggression,” was authored by Wenche Wang and Hua Gong.