Many people don't like lawyers. The old joke is "everyone hates lawyers until they need one". One of the many reasons why people don't like lawyers is the fact that sometimes a lawyer must defend a guilty person, and sometimes that person is acquitted for whatever crime they are accused (and presumably guilty) of. I would posit, however, that if a good lawyer defends a guilty person, and that person goes free, it is not the good lawyer's fault, but instead the bad lawyer is to blame (the one charged, presumably, with prosecuting the crime). In other words, the law protects the innocent and prosecutes the guilty, and when justice isn't served it's because some lawyer made a mistake.
consider the following example:
A man assaults a woman with a gun. Assume that there are no problems with search and seizure, that there are no "technicalities" which would lead to an acquittal. The good lawyer is defending the man, the bad lawyer is the prosecutor. The man is charged with criminal assault.
The burden of proof is on the prosecutor to prove that the man is guilty of all elements of the crime. For assault, he must prove that the man was the person who indeed pointed the gun, that he intended to point the gun, and that he intended to cause her to have fear. The prosecutor must prove all of these things in order to prove assault. The defense need only prove one element is missing...
so what do they do?
Bad Lawyer: bad lawyer only has one witness: the victim... he questions her extensively, proving that the man indeed pointed the gun, and that he made threatening remarks proving that he intended to assault her. he finishes.
Good Lawyer: I have no questions your honor, and I move for summary judgement because the State has failed to make a prima facia case [summary judgement is when the judge decides that there is not enough evidence for the jury to decide, so the judge decides for them; a prima facia case is the burden on the prosecution to meet all of the 'elements' of the crime in their proof]
Judge: on what evidence do you make this motion?
Good Lawyer: the prosecution did not prove that the victim was afraid.
Judge: [looks at the transcript of her testimony] you're right. motion granted, case dismissed.
so the man goes free. the good lawyer did his job, the bad lawyer didn't, and the criminal goes free. two days later the man kills the woman. is it the fault of the good lawyer for doing his job and "getting his client off"? no. It's the bad lawyer's fault for not knowing the law and proving his case.