A sneaky, underhanded lawyer is a pettifogger. If your neighbor hires an unscrupulous quack to sue you, you might call his attorney a pettifogger.
You don't hear the word pettifogger much these days, since the word is fairly archaic, but you might come across it in an old book. A bad lawyer, or pettifogger, used dubious means to get clients and to win cases. The mid-16th century word itself combined petty — "small," from the French petit — with the obsolete word fogger, "underhanded dealer," which probably came from a wealthy 15th century Bavarian family of merchants, the Fuggers.