Trained as a lawyer, Braithewaite served as the city's prosecuting attorney. He also had extensive training as an investigator. He was good friends with the city's defense attorney Lee. Nearly all of his cases were for minor offenses, which Braithewaite considered quite boring. When Lee - tired of pleading fines for intoxicated miners - inquired if he could turn up a good smuggling case Braithewaite's response was that he wished he could.
In an alternate 2270, Braithewaite boarded the USS Enterprise to escort Dr. Georges Mordreaux to a penal colony. In that alternate timeline he was later murdered by a violent future version of Dr. Mordreaux. (TOS novel: The Entropy Effect)