Amateur hour: thinking from scratch about a question that I'm sure has received professional attention:
On my morning commute yesterday, I was quizzing a New York public defender about her daily routine and work flow. Not surprisingly, most of the clients she handles are never indicted and perhaps 5% of cases come to trial; the rest are dealt with either through plea bargain or administratively. Other tidbits: often she does not know herself whether her client is guilty or not, and often it's prudent for someone who is innocent (or may be innocent) to plea bargain, because a jury trial is always a roll of the dice - particularly when you have inner city defendants likely to be judged by a more affluent and educated jury.
What I found myself wondering: how competitive or adversarial is the process, and how do you measure success? If, as a defender, you believe that the system is stacked against your poor clients, that most of them are not guilty of much and that the state is likely to punish them disproportionately, you would measure success pretty much as your clients would -- by how well you minimize their punishments. Do your clients, on average, receive lesser penalties than those of your peers? If on the other hand you consider judges and prosecutors more your colleagues than your adversaries, you would judge yourself by some not-really-measurable sense of whether justice, roughly, was done in the vast majority of cases that are resolved without trial. Ditto of course for prosecutors, who are by reputation competitive, aggressive, driven to ring up as many convictions as they can.
I'll have to ride with this 'train friend' again soon, and ask her...