Who is Mr. Jamison? Why does Cassie like him so much

Mr. Jamison is a lawyer whose family was originally from Vicksburg, he inherited land that had once belonged to the Grangers from his father and sold it to Paul Edward Logan in 1918. Cassie likes him for always calling her mother "ma'am." He offers to back the credit of those who boycott the Wallace store and shop in Vicksburg, and he stands opposed to those who want to hang TJ, arguing with them and even blocking them from driving away by putting his car in the middle of the road.