The impact of lengthening the school day on substance abuse and crime: Evidence from a German high school reform

In the 2000s, a major educational reform in Germany reduced the academic high school duration by one year while keeping constant the total number of instructional hours before graduation. The instructional hours from the eliminated school year shifted to lower grade levels, which increased the time younger students spend at school. This study explores the impact of the reform on youth crime rates and substance abuse using administrative police crime statistics, administrative student enrollment data, and a student drug survey. The staggered implementation of the reform in different Länder-age-groups allows for a difference-in-difference approach. I find that the reform resulted in a decline in crime rates, which is almost exclusively driven by a reduction in violent crime and illegal substance abuse. Regarding the latter, the rate of illegal cannabis consumption strongly declined; however, no significant effect is detected on cannabis dealers or the consumption of other illegal drugs. The survey evidence further suggests that decreased cannabis consumption was not driven by a shift of consumption into 'school hours'. The results point to an 'incapacitation' effect of schooling due to the increased instructional hours at lower grade levels.