Between the 2009–2010 and 2010–2011 seasons, the National Football League (NFL) repositioned one of its officials in order to prevent injuries among officials. This creates a quasi‐experiment for studying how a change in the extent of policing affects detection of offenses. Using play‐by‐play data from the 2009–2010 and 2010–2011 NFL season, I estimate how the detection of offensive holding changes when the positioning of an official changes. I find that there is approximately a 20 increase in the number of offensive holding penalties called after the NFL repositioned the official. Penalties called on defensive linemen fell as a result of the repositioning. Overall, there was no change in the total number of penalties called. Using the estimated change in the probability of a penalty, I estimate the probability of an official calling a penalty. I infer that NFL officials detect approximately 60% of crimes committed on the field. (JEL K4, Z0, D0)