Swiftness and delay of punishment

Abstract We study how the swiftness and delay of punishment affect behaviour in the context of speeding offences. Using rich administrative data from automated speed cameras, we exploit two quasi-experimental sources of variation in the lag between an offence and the sending of a ticket. At the launch of the speed camera system, administrative bottlenecks created delays of up to three months. Later, we implemented a protocol that randomly assigned tickets to either swift or delayed processing. We present two main results. First, delays reduce payment compliance: timely payments fall by 7 to 9% when tickets are sent with delays of four or more weeks. We also provide evidence suggesting that very swift tickets – sent on the first or second day after the offence – increase timely payments. These findings align with predictions from expert scholars elicited through a survey. Second, speeding tickets cause a strong, immediate, and persistent decline in speeding. Although swift tickets generate sizable mechanical benefits, we find no robust differential effects of swiftness or delay on subsequent speeding behaviour. This challenges widely held beliefs, as reflected in our survey. Finally, we outline a simple framework of learning and updating that explains our findings.