Rockford starts with the "the legal system isn't perfect but it's the best we've got" attitude, so I think he's always been aware of it's failings.
The story indicates he's lost cases before, but not how many. Naively, Rockford expresses surprise that the Orcs, through Sen. Carrington, are breaking the law of the land, and Sen. Carrington calls him an "idealist" unduly influenced by Aghavni.
Rockford seems to be getting jaded enough to potentially cross the Rubicon, and this comes at a time when he's getting hammered on all sides with his personal and family issues. Players can judge for themselves if this transition is realistic.
One of the ironies is Sen. Carrington wanting Rockford to run for office to oppose an incumbent who he perceives as "weak" on justice, all while breaking laws with impunity himself.
IM has stated that the two primary themes of the AVN are family and justice, so I am interested to see where Rockford goes on a "dark" path if he feels he has to take justice into his own hands or gets comfortable with breaking the law himself.