Let me state first that I am a lawyer but I do tax and not criminal law. I took the class, though and this is the kind of thing discussed ad nauseum in professional responsibility courses, etc.
My take on this is that if you aren’t going to believe the defendant when he said he didn’t do it, why do you automatically believe him when he says he did? Other lawyers have not been very receptive to this, and normal people even less so. I like it, though.
The more traditional answer is that every defendant deserves a good defense even if he’s guilty as sin. It’s the job of the defense attorney to muster up the evidence in favor of his client and put it up in front of the jury to try and create a reasonable doubt in the jury’s mind about the defendant’s guilt. So, a defense attorney doesn’t really say “he didn’t do it,” he only says “there’s a reasonable doubt about whether he did it or not.”
Also, remember that it’s not always about whether he did it or not. Sometimes it’s about what exactly he did. For example, maybe the charge is murder 1 but the defense attorney thinks the facts don’t show premeditation (or whatever), so the charge should really only be murder 2.
No. The first two items below are kind of my own ideas, and many people find them wrong, and some even think I’m evil because I think like this. The third one is more straightforward.
First, by definition a defendant is not guilty of anything until the jury finds him guilty, so it is impossible for a defense attorney to know his client is guilty.
Second, just because a defendant tells his defense attorney that he committed the crime doesn’t mean that the defense attorney knows his client committed the crime.
Third, perjury is lying under oath about facts. When a defense attorney puts a witness on the stand, the witness simply relays facts, what they saw, heard, etc., and when and where. They don’t simply say “the defendant is not guilty.”
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