CAB RIDE LEADS TO DEADLY ENCOUNTER - When a publishing executive is found murdered, Detectives Briscoe (Jerry Orbach) and Green (Jesse L. Martin) find that the dead man's last moments were spent arguing over a taxi -- and their suspect (guest star Steven Rishard) proves to be a racist who was outraged when the African-American victim took the cab he was trying to hail. Executive A.D.A. Jack McCoy (Sam Waterston) and A.D.A. Serena Southerlyn (Elisabeth Rohm) face a potential test case when the defense attempts to classify the suspect's avowed racism as a mental illness.