Complex sentence: He went to work for the New York City Transit Dept for the next two decades, doing examinations before trial, which meant he represented the Department in depositions by opposing counsel, testifying to various records in the city's possession.
Split into simpler sentences: He went to work for the New York City Transit Dept for the next two decades, doing examinations before trial. He represented the Department in depositions by opposing counsel, testifying to various records in the city's possession.