Apollo Justice is a defense attorney working for the Wright Anything Agency. He is notable for his involvement in a test trial for the Jurist System, an effort to reintegrate the jury into court proceedings, along with co-council Trucy Wright and Prosecutor Klavier Gavin and mentor Phoenix Wright.
Apollo Justice is highly sarcastic and critical. He often makes blunt comments concerning his mentor Phoenix Wright's piano playing in particular. He occasionally even shows some disdain for some of his clients. He also has a vain side; he frequently makes puns out of his own name, and he practices his shouting for hours at night, calling it his "Chords of Steel", which sometimes makes his voice raspy. He frequently worries about and feels sorry for Trucy Wright, and is confused by Phoenix and Trucy's odd relationship.
In court, Justice is noticeably more unsure of himself and more easily flustered than Phoenix Wright ever was. He is just as determined, however, although he tends to base his arguments more in fact and discernible thinking than his mentor did.
(Source: The Ace Attorney Wiki)