There is an easy test to see whether you would make a good prosecutor or a good defense attorney. Ask yourself - how do you feel about police? Do you trust them? Do you think they are well intentioned servants of the public who truly make an effort to protect and to serve? Do you think that, by in large, they tell the truth about the arrests they make, that they rarely, if ever, lie to get a conviction? If you feel that way, you would make a good prosecutor. If you do not, you would make a good defense lawyer.
How do you feel about the government? About authority in general? Do you trust the government to do the right thing most of the time? Are you in favor of authoritarianism? Do you see yourself as being authoritarian? (Tough one there, because most who are authoritarians have a great deal of trouble recognizing that they are.) Do you enjoy positions of authority, where you control the destinies of others? Become a prosecutor. If, on the other hand, you do not trust the government as far as you could throw it, if you detest authoritarianism and all those who practice it, then become a defense lawyer.
And one comment on defending people you "know" are guilty. Understand something. Defense attorneys do not condone the actions of their clients. Defense attorneys do not sit down with their clients and help them dream up lies which are then foisted off on the jury. These are things that defense lawyers do not do. What do they do?
The main job of a defense attorney is to make sure that. if the client is going to be convicted, that his/her client is convicted of the proper crime. That's right, you heard me. Prosecutors routinely overfile cases. An assault with a deadly weapon gets filed as an attempted murder. The defendant is guilty of the ADW but not the attempt murder. A defense attorney who comes out of a jury trial with a conviction on ADW but an acquittal on the attempt murder has done a huge service for his client. Huge. And for all you moralists out there, where's the harm to the justice system in that scenario? None. It's a win-win.
I have tried over 400 jury trials, more than half of them being felonies. I can only remember one trial where I felt a guilty man went free - and it was a misdemeanor, DUI case. I have had dozens of cases that resulted in overfiled charges being reduced to crimes that were appropriate for the facts of the case. Honestly, I did not feel good about the DUI guy that got off. With regard to the other cases (overfiled charges being reduced to appropriate convictions), I feel great about all of them.
Let me leave you with a quote that is up on the wall of my office and on the office walls of many other public defenders I have known. (I don't have this one memorized, so I will paraphrase it the best I can.) It goes like this:
"I am a criminal defense attorney. On a daily basis, I am confronted by, and have to deal with, the lowest aspects of the criminal justice system - people who have no conscience, people who have no regard for fairness, ethics or the humane treatment of other human beings. People who think nothing of lying directly to me and/or committing perjury by lying on the stand in order to get the result they want. And it is my sworn duty to protect my clients from such people to the best of my ability at all times."