pettifog

[pet-ee-fog, -fawg] /ˈpɛt iˌfɒg, -ˌfɔg/
verb (used without object), pettifogged, pettifogging.
1.
to bicker or quibble over trifles or unimportant matters.
2.
to carry on a petty, shifty, or unethical law business.
3.
to practice chicanery of any sort.
Origin
1605-15; back formation from pettifogger, equivalent to petty + fogger < Middle Low German voger or Middle Dutch voeger one who arranges things; akin to Old English gefōg a joining
Related forms
pettifogger, noun
pettifoggery, noun
Can be confused
ambulance chaser, mouthpiece, pettifogger, shyster.
British Dictionary definitions for pettifog

pettifog

/ˈpɛtɪˌfɒɡ/
verb -fogs, -fogging, -fogged
1.
(intransitive) to be a pettifogger