Hammond was a skilled defense attorney. But... he defended clients not for their sake, but for his own. [...] He never trusted his clients, that one. The only thing he trusted was his own ability. [...] He won that innocent verdict for no one but himself.
Robert Hammond was a gifted criminal defense attorney working at Grossberg Law Offices and a colleague of Mia Fey (clearly for a long while, considering Maya Fey recognized his photograph many years later), but the only thing he trusted was his own skill; he never trusted his clients. This put him at odds with some of his colleagues such as Mia Fey, but his dedication and skill were never in any doubt.
In 2001, Robert Hammond represented Yanni Yogi in the DL-6 Incident when Gregory Edgeworth was murdered. Due to the strong evidence and testimony against his client, Hammond told Yogi to plead temporary insanity to escape a guilty verdict. The plan worked; Yogi was a free man, but his life took a turn for the worse as well: his fiancee killed herself, he was fired from his job as a bailiff, and his friends abandoned him. Hammond himself left Grossberg's company and kept a very low profile for the next decade and a half.
Fifteen years later, Hammond went to Gourd Lake because of a letter from Yogi. They met, and Yogi shot and killed Hammond inside his shack. Yogi took Hammond's coat and disguised himself as his former lawyer to carry out a plan to frame Miles Edgeworth for the murder. His plan almost succeeded, if it were not for Edgeworth's own defense attorney Phoenix Wright, who eventually exposed Yogi as Hammond's true killer.