As criminal defense lawyers we don't always represent the nicest of people. Some of them are difficult to get along, and want to fight you at every step. Many lack basic social skill - that is usually why they are in your office in the first place. Despite all that I generally like almost all of my clients; when you get to the bottom of their problem, it often is an otherwise good person who made a bad decision. Of course, getting to the bottom of things often takes time and effort.
The reason why I started thinking about this arose out of the Cameron Todd Willingham case. Except for a few people, most people who have looked at that case now believe he is innocent. One of those few people is one you would not expect - his trial lawyer. He has described him as a sociopath, and still believes he is guilty. It's pretty clear he didn't like him.
Todd's lawyer is not the first to think his client guilty - although his conduct may be to the extreme. The fact is, most defendants are guilty of something. The truly innocent client is rare, and one most lawyers dread getting because of the enormous burden you carry with you. Even if you know you're client is guilty, that doesn't mean you don't give them the best defense possible. The State already has a prosecutor aimed at convicting them, and they don't need any help. If you are not prepared to make the State do its job, and do everything you can for your client, you need to do something else; maybe something that doesn't involve people's futures.
Do you have to like your client to effectively represent them? Not necessarily, although its nice when you do. Good criminal defense lawyers are passionate about something else; you can call it justice, or something else, but they are passionate about making sure the system works, and the letter and spirit of the constitution is put into effect. That is why good lawyers can represent the people who society considers the most reprehensible.
Effectively representing someone means more than knowing the law though. You also have to know your client. There's a reason why they are in the position they are in, and you need to find it. In doing so, you usually discover they are not the person the State is portraying them to be. And yes, you might even start to like them.
It always find it odd that people who are fond of saying "hate the sin, love the sinner" don't apply that to criminal defendants. Society, with a lot of help from the prosecutor, is quick to jump all over something who does something bad. Their lawyer shouldn't do the same; they have a story to tell, and its the lawyer's job to tell. You don't have to like what they did - there's probably something wrong with you if you do - but you do have to find the reason why did it. Hopefully its something other than that they are sociopath.
So you don't have to like your client, but it helps if you do. After all, it is you and him (or her) against the government.