Criminal lawyer? Isn't that a redundant term?
All kidding aside, the main job of a defense attorney seems to be to make the state prove its case. Here's the thing about the criminal justice system -- in a jurisdiction with an effective prosecutor's office and solid police force, the accused is guilty as can be about 95 percent of the time. In those situations, all a defense attorney can do is make sure his or her client receives a fair trial and that justice is done.
Anyone interested in going into criminal law should take a hard look at being a deputy prosecutor. Those who like law and order and crusading for justice would be better off prosecuting criminals than defending them.