I tell my students, if you ever become comfortable with your role as criminal defense lawyer, it's time to quit. It should be a constant source of discomfort, because you're dealing with incredible moral ambiguity, and you've been cast into a role which is not enviable.
A criminal trial is never about seeking justice for the victim. If it were, there could be only one verdict: guilty.
Scientists search for truth. Philosophers search for morality. A criminal trial searches for only one result: proof beyond a reasonable doubt.