The defendant school district contracted with the defendant transportation company to transport special needs students to and from school. The plaintiff alleged that a bus driver for the transportation company molested her daughter during the rides to and from the school. The evidence showed that the bus driver acted suspiciously during his employment, but no history of abuse. The plaintiff sued the school district for negligently retaining a bus driver who they should have known had a propensity to abuse children. Should courts regard an employer's retention of a problem-prone employee as sufficiently 'causing' their employee's intentional tort?