Hypothetical Business Situations

Should a defence attorney work for a client he or she believes is guilty?

I have been wondering the answer to that question for years, but i think that the attorney just wants to get paid and they want to have attention in the media. Say for instance a women kill all ten of her children, and the attorney gets them off, then all the criminals will go to that attorney and he or she will have money on top of money and everyone will know that they have won many cases. But then again sometimes i think that the attorney is sometimes confused by some of their clients, or they probably feel threathed if they don't defend that person.