chslaw beat me to it again.\n\nHe's right.  You have to prove 1st that your lawyer failed to exercise the kind of professional duty you can reasonably expect. (sounds like you've got that).  But 2nd, you have to prove that his failure to do so caused your case to fail.\n\nGood luck finding an attorney to sue.  In my experience, lawyers are very hesitant to sue their own unless there's a very egregious screw up.