We estimate the role that law enforcement officer experience has on the probability of punishment, using a unique data set of tickets issued by the Idaho State Police linked to human resource records. All else equal, officers issue fewer tickets earlier in their career than later in their career. Quasi-exogenous shocks to an officer’s task-specific experience, generated by law changes, cause a temporary reduction in the frequency with which a subset of troopers “use” those laws, creating disparities in the likelihood that individual citizens are cited for law violations. The reduction in ticketing in response to a law change is largest for newer troopers, and law changes later in a trooper’s career have a smaller effect on his use of that law
