Questions are answered as to whether taxicab partitions between drivers and passengers reduce assaults. Assaults on Baltimore, Maryland, taxi drivers decreased 56% the year following a citywide mandate requiring partitions between taxi drivers and passengers. Data also show that between 1991, when only 5% of cabs had shields, and 1998, when all taxis had shields, assaults decreased 90%. Confounding factors such as annual changes in city population, crime rate, robberies, unemployment, and drug arrests are addressed by comparing the 1991 assault rate for the shielded cabs of one taxi association with a similar association without shielded cabs. This analysis shows that in 1991 an unshielded Baltimore taxi driver was five times more likely to be assaulted. Using linear regression to account for the time variation in factors from 1991 to 1998, the results indicate that reduced driver assaults correlated the most with population changes, improved policing, decreases in robberies, and the percentage of shielded taxis. A related economic analysis yielded a 17-to-1 benefit-to-cost ratio of estimated savings from reduced injuries versus the costs of citywide shield installation. The results support the Baltimore shield mandate and argue for shields in other cities.