Is there any defence for what criminal defence lawyers do?

"I don't think too many innocent people are convicted but a lot of guilty people get off." -- Mike Bungay

This is not a question of whether "criminal defence lawyers" do distasteful things; undoubtedly they do. Instead, it is whether we would prefer to live in a society without them. An innocent convict is a double injustice, once for sacrificing an individuals' freedom for nothing, and then for denying wrongdoers responsibility. The corollary is a two-way good: by keeping an innocent person free, "criminal defense lawyers" also make it possible for the guilty to be brought to justice. Unfortunately, innocence and guilt do not translate easily to a balance sheet, and even if we had the figures, we could not simply ask whether at least half as many innocent people remain free (we value each part of the two-way good differently) as those guilty who get off.

Still, there are compelling reasons to consider "criminal defence lawyers" a boon to society. First we need to be honest about their role. It is to defend the integrity of the justice system, not criminals. The only "criminal defence" lawyer I can think of is the consigliere from The Godfather. As important as it is to relate to their clients on a human level, their role is impersonal in that they work to ensure fair trials, not to judge individual innocence or guilt. Such fairness is even more important when the other party to proceedings is almost certainly better-resourced.

This same principle is one justification for the adversary system we use. So-called "criminal defense lawyers" are particularly essential to this system, as it places the entire onus on them to bring the best case possible for their clients. This system and the attorneys are so entwined that any defence of this system vindicates their role. One defence is ancient, lying behind the Code of Hammurabi.

The Code requires that, if a building falls and kills its owner, the builder must be put to death. While extreme to modern standards, it reflects a very important understanding: after an incentive to avoid shortcuts, the builder is in the best position to ensure sound construction. So too with the parties to adversarial proceedings; they have the greatest capacity (and incentive) to ask and answer the right questions for arriving at a just result.

The weakness in this argument is that it assumes lawyers meet the onus on them. The fact that some advocates have better reputations than others suggests this isn't always true; still, they can not be solely culpable for the failures Bungay mentions, given the evident biases of some judges and juries.

Bungay himself says, remarkably, that the majority of people charged with murder are acquitted. If he is right that a majority, too, are innocent of the charge (and especially if this is common to other offences), this alone justifies defence lawyers role according to the rough calculus from the beginning of this discussion. If not, the other - principled - arguments make a compelling back-up. If neither empiricism nor philosophy sway, empathy still might: if charged with a crime, where would you want to live? Who would you call?