The Collaborative International Dictionary of English v.0.48:

Pettifog \Pet"ti*fog\, v. i. [imp. & p. p. Pettifogged; p. pr.
   & vb. n. Pettifogging.] [Petty + fog to pettifog.]
   1. To do a petty business as a lawyer; also, to do law
      business in a petty or tricky way. "He takes no money, but
      pettifogs gratis." --S. Butler.
      [1913 Webster]

   2. To debate or quarrel over unimportant, trifling matters.
      [PJC]

   3. To use subterfuge, deception, or flattery for any purpose;
      to practice chicanery.
      [PJC]