Nope, or at least he isn't supposed to. Not only can it get the lawyer disbarred, it can get him imprisoned. Having said that, happens all the damn time: MOST lawyers know if their client is guilty. This is one of the major ways in which lawyers and the law have been warped by unethical greedy lawyers: the purpose of a lawyer is to see that you are treated fairly and justly under the law. It is not their place to see that you get "off".