what is different about judge tanner when cole sees him in court and when he sees him at the healing circle meeting what might this change symbolize

The Judge wasn't at the circle to pass judgment, he was there as a part of the community. Thus, he blended in..... he was just another face.

He recognized one man as Judge Tanner. The last time Cole had seen him , the judge had been wearing a black robe at the arraignment hearing in juvenile court when Cole first pleaded guilty. Tonight Judge Tanner wore no robe and was dressed in blue jeans and a
sweater.