Despite what the narrator say, it is the jury that decides the fate of the defendant and in this case "freed" the defendant. The attorney did not free him, the attorney merely defended him.
The narrator, Judge says that "martin strang was one of the greatest criminal lawyers ever to appear before my bench" only an attorney at law can appear and represent a client in a courtroom. A lawyer can only act as an advisor but does not represent a defendant in a court of law.