I hate to point out the obvious, but you can't say anything meaningful about the effectiveness of lawyers without separating their clients into the ones that we

I hate to point out the obvious, but you can't say anything meaningful about the effectiveness of lawyers without separating their clients into the ones that were guilty and the ones that weren't. It's very probably a wrong assumption that public and private lawyers have the same percentage split. And if the system actually worked, then a good lawyer shouldn't affect the conviction rate of the guilty...