Let me take another stab at answering your precise question here more simply and directly. Suppose I’m representing someone I know raped a child. About the only way I could have actual “knowledge” of his guilt that the prosecutor didn’t also have and could share with a jury to assure a conviction is if the defendant himself told me he did it. Such inside knowledge can’t be allowed to affect my representation because the ability of a defendant to communicate openly and honestly with his lawyer is essential to the defense function. And the integrity of the defense function is essential to society’s interest in not convicting the innocent, i.e., in Justice. I “do justice” by not letting this privileged information affect my representation.

(On the other hand, if I myself don’t actually “know” for a fact that my client is guilty I don’t see how there could be even the slightest imputation of any “injustice” in testing the state’s evidence and arguing to the jury that the state hasn’t proven its case beyond a reasonable doubt. We “do justice” by doing so. While this undoubtedly leads to the acquittal of some guilty defendants, it directly serves society’s interest in not convicting the innocent, i.e., in Justice.)

Suppose I know (and everybody else knows) the client is guilty of child rape but I can get the case dismissed with a motion to suppress. Although the client’s injustice against the child may in God’s eyes dwarf the injustice committed by the police against him, it’s nevertheless true that the police committed an injustice against him, and by redressing that injustice I “do justice.” Furthermore, by redressing that injustice I assist in deterring police from committing the same kind of injustice against other people. By assisting in that deterrence I “do justice.”

It’s not the end of the world if a guilty man goes free. Most guilty men do go free (unless and until they’re caught). I presume this realization made it easier for Ben Franklin to say that it was better for 100 guilty men to go free than for 1 innocent to suffer. If Justice is the absence of crime, the freeing of a guilty man is not a great injustice (especially relative to the conviction of an innocent man — which unlike the freeing of a guilty man IS a crime, or relative to the injustices that would be caused by lawyers letting their inside knowledge of a case negatively affect their representation or by letting police misconduct go undeterred): If he is in fact a dangerous man, the risk to any other individual of the freed criminal committing a crime against him is extremely remote. (There are already plenty of dangerous people in the world besides him.) The fact that he escaped punishment would not significantly lessen whatever general deterrence attaches to the fact that many others don’t escape punishment. And the punishment the guilty man escaped would not have undone the crime he committed.

Part of the problem is that justice is a big word, subject to different people investing their own interpretations into it. That’s not my fault. It’s the nature of the beast. You could just as easily say there’s a certain amount of ambiguity if not disingenuousness and propoganda in the Dept. of Justice claiming the word justice for what it does. I came up with the specific formulation of my current definition – Justice is the absence of crime – a while ago in a comment thread on one of Bennett’s posts, but the definition is consistent with what I’ve been trying to say from the beginning, and I think the definition is accurate and consistent with the root meaning of what people mean when they use the word justice. (That is, the definition that reflective people might arrive at after a process like that in one of Plato’s dialogues.)

I didn’t say before that justice is simply and only due process. Rather, procedural justice is a real and critical aspect of justice, but still only an aspect and a means to the end of Justice — i.e., the absence (or on a more practical level the reduction) of crime, including the crime of convicting the innocent.

As I see it, there’s two ways in which the role of the CDL is to “do justice,” despite the fact that we fight against convicting the guilty. The first and most fundamental and I think least controversial is the system-wide aspect of the CDL’s role highlighted by Justice White’s opinion. It’s society’s “interest in not convicting the innocent” (i.e., not any apathy towards Justice — quite the opposite) that “permits” and “requires” defense counsel to fight just as hard to free the guilty as he would to free the innocent. To permit defense counsel to do anything less would be seriously detrimental to society’s interest in not convicting the innocent.

The second (though naturally related) way is in individual cases considered individually rather than systemically. There is a rebuttable presumption that locking a person up in a cage like an animal is a crime. The CDL fights on the side of that presumption, regardless of his client’s guilt or innocence. He fights against what looks and smells like a crime, like an injustice. The prosecutor, pursuant to his own job, may believe that in this instance, in this case, the defendant should be locked up in a cage like an animal. It’s not the job of the CDL as CDL to make such judgments. In many cases the CDL won’t “know” whether his client is guilty or not. But even when he “knows” his client is guilty (perhaps only because of his role as the client’s lawyer and confidences the client has shared with him), his job as CDL is not to make the judgments the prosecutor is charged with making, but to fight against what looks and smells like a crime. (Furthermore, even when he knows his client is guilty the effectiveness in serving Justice in its root sense of the punishment or “justice” the prosecutor has in mind for his client is doubtful.) By doing so, he fights for justice.

It may seem to you like I’ve shifted my position and changed my definitions over time, but if you look back on what I’ve written before you’d see I really haven’t.

There’s a sense, which I’ve never disputed, in which it’s true to say that the prosecutor’s job is to “do justice” while the CDL’s job is only “to defend.” As CDLs we’d rather the prosecutor endeavor to “do justice” rather than simple-mindedly and relentlessly endeavor “to convict” and send defendants away for as long as they possibly can, and we don’t want the zealousness of our defense to be affected by whether we think our client is “guilty.” But I think it’s truer to say, and more reflective of the true moral stature of CDLs relative to prosecutors, that CDLs “do justice.”