论文题目：Mello, Steven, Speed Trap or Poverty Trap? Fines, Fees, and Financial Wellbeing. Job Market Paper
There is widespread financial fragility in the United States and anecdotal evidence that even small, unplanned shocks may have adverse effects on the financial situations of fragile households. However, causal evidence on the implications of unanticipated,transitory expense shocks for low-income individuals is scarce. I study the impact of fines for traffic violations on financial health, earnings and employment, and measures of borrowing and consumption using administrative data on traffic citations in Florida linked to high-frequency credit reports and payroll records. Leveraging variation in the timing of traffic stops with event study and difference-in-differences research designs, I find that following a traffic stop, individuals experience increases in financial distress, decreases in the probability of positive payroll earnings, and reductions in measures of consumption and borrowing. The effects are concentrated among the poorest quartile of drivers, where payroll employment falls by eight percent and the increases in financial strain induced by a $175 fine are observationally similar to what would be predicted by a $900 earnings decline. While adverse effects are partially caused by constraints on car usage due to driver license suspensions, an important mechanism appears to be a poverty trap whereby shocks have a compounding effect for the disadvantage population. I conclude by estimating that the average traffic ticket is associated with at least a $500 welfare loss and discussing this magnitude’s implications for optimal policing.