in criminal defense, you basically have four categories of clients:
1) People who are not guilty, and the government cannot convince a jury they are.
2) People who are not guilty, but the government can convince a jury they are.
3) People who are guilty, and the government can prove it.
4) People who are guilty, and the government cannot prove it.
Each of these categories needs to be treated differently.
Categories 1-3 are pretty straight forward.
1) If a guy is innocent and the government can't prove they're guilty, you litigate and win.
2) If a guy is innocent but the government can convince a jury they're guilty, you investigate and fight like the dickens to allow the truth to come out in court, then litigate and win.
3) If a guy is guilty and the government can prove it, you convince him to plea guilty and say sorry.
4) It's the last category -- guilty people that the government cannot prove guilty -- that gets people all tripped up. "How can you defend guilty people!?"
Before answering that question, however, we need to dig into the assumptions underlying the question itself.
The key assumption, I think, is that "If a guilty person isn't punished for his crimes, he has gotten away with them -- and this is unjust."
This only makes sense of we assume two things:
First, that governmental punishment is the only legitimate and meaningful source of punishment;
Second, that crimes OUGHT to be punished by government.
I don't think either of those is necessarily true. Consider a man who slaps his wife, and his wife leaves him, but never reports the offense to the police, so he is never punished by government. But of course he loses his wife. He has technically violated "the law," and not been punished by government. But he has been punished. He has received the natural and normal consequences of his actions -- the loss of his wife. And would it necessarily be more just for the governmen to step in and slap him on the wrist for this offense? No. It is best, I submit, for the issue to be addressed between the two of them directly.
There are many other cases where a "crime" need not be punished by government. An insane man attacks a psych ward employee in a fit of madness, and kills him. Punishment will serve no purpose, as the person lacks the mental resources to "learn from his mistakes." Rather, the "right thing to do" is not to punish, but treat the person, and keep him in circumstances where he will not hurt another.
Seems to me there are many other cases where the violation of a law need not be punished by government in order to be adequately addressed. Many sins, after all, are their own punishments.
So let us conclude that there is not necessarily a violation of the deep moral law if a person commits a crime and is not punished by government. Rather, let us conclude that government should only punish crime where punishment is justified and useful under the circumstances.
So then, what is the justification of punishment?
The American system is premised on the idea that punishment is only justified if the government has met its burden of proof. NOT merely that a person is guilty -- but that the government has PROVEN a person is guilty.
And who is to decide that?
The accused cannot be relied on, for obvious reasons. Sometimes they may falsely deny a crime because they want to avoid punishment. Sometimes they may falsely admit to a crime to protect someone close to them, or because of mental infirmity. And people do falsely admit to crimes. All the time.
The government cannot be relied on, also for obvious reasons. Unless the government is given a check and balance, it can -- and will -- exercise arbitrary punitive power, to the detriment of individual rights and the integrity and predictability of society of a whole.
So who is to be relied on?
The evidence, weighed out and balanced in court.
And how is this evidence to be weighed? Well, that's determined by the system. And the rules of the game say that defendants have a legal and moral right to plead not guilty, even if they are.
I think it's for the best of the system. Because again, just because I'm guilty doesn't mean the government should be able to punish me. The government needs to play by its own rules if it wants to punish me -- and one of those rules is getting the evidence together and convincing a group of people that i did what they say i did. That's how the system works.
So if the system is designed to work that way; and if the system says I have the legal and moral right to plead not guilty even if I am ... and that the government is responsible for proving I'm guilty in front of detached jurors ... then why shouldn't I?
And this brings us back to the first point. If the government does not punish a crime, that may or may not be the right outcome, depending on the circumstances. The rules say that the government has to put together case enough to prove I'm guilty -- evidence enough to convince people who know nothing about me that I did what they say I did.
If they can't do that, therefore, they should not punish me.
And that's what it comes down to. If I defend a guilty man and the government fails to convince the jury that he's guilty, the government does not punish him. But:
1) That doesn't mean he gets away with it. As discussed before, there are many ways we can be punished for our actions that don't involve governmental action. Sometimes (though certainly not always), those punishments are actually more effective than the governmental action itself.
2) The government has set the rules of the game. They've decided to only punish people if they can prove it. If they can't prove it, they can't punish. Regardless of guilt or innocence. Their rules. I see no problem playing by their rules in deciding whether they get to punish somebody.
Why should I apply a higher standard -- a standard that treats the government as God, and their punishment as the only true punishment -- when the government doesn't even assume that level of arrogance?