The effect of monitoring and crowds on crime and law enforcement: A natural experiment from European football

Technological advancements like the presence of smart phones and body cameras have led to increased monitoring of police, but little evidence exists on their impact. We address these problems using data on fouls from football matches in five European football leagues over six seasons. This period contains exogenous changes in monitoring rule enforcers through introduction of Video Assistant Referee review and limited bystanders from Covid-19 restrictions. Results from difference-in-differences models estimated separately for each league indicate that both events influenced the number of fouls called with substantial heterogeneity across leagues and home/away teams