Devil\'s Advocate-Necessary Evil

Devil's Advocate- Necessary Evil

Advocates are called by many names like Sharks, Devil's Attorney, Legal Eagle, Liar (Common Misspelling) and many. Why, we are being called like this? Why society sees lawyers as common criminal liar who is in a suit competent to lie in front of law? Is it ethical to defend a criminal? How can a lawyer try to save a criminal without moral?
Generally people think that lawyers are defending the criminal because of money. Not that because all lawyers are money minded but to uphold the justice and chance to explain himself. If you ask me, is it ethical to defend a criminal in court of law? I say yes, it is ethical as well as a duty of an advocate to defend a man in court of law till he is proven guilty.
How is it ethical and duty of an advocate to defend a criminal? It started in England 1840(Courvoisier case) that an innocent man has sentenced to prison that no lawyer was ready to defend the man because everyone believed that he was the real criminal until they caught the real one. It is very well justified in that same case that a man have right to defend himself in court of law as a legal right as well as natural law of justice.
What if the accused confess to the advocate that he committed the crime? Is it right to defend a known guilt man in court of law? Duty of a defense lawyer is to zealously represent his client within bounds of law. Duty of a lawyer is not to "do justice" but to defend. In contrast duty of a prosecutor is not to prosecute but to "do justice". There are two things which a lawyer has to analyze, what the accused actually did? And which he did is legally guilty? In order to arrive to arrive at conclusion a man is really guilty is in court of law by examining the case in eyes of law. Law only can decide whether a man is guilty or not.
Yes lawyers are necessary evil for the society. People may be ignorant to say it is wrong or not ethical to defend a criminal but it's the ugly truth that they need the same devils to save them if they got into any trouble.