My elder brother (who is now a Metropolitan Trial Court judge) and I used to watch this every week back in the early '60s. I don't remember much of the episodes except I know I enjoyed most of them. It has a very inspiring trumpet led theme music as the camera took a long bird's eye view panning shot of a majestic courthouse with Greco-Roman architecture.
I do remember Atty. Preston, the elder, (E.G. Marshall) often arguing on the basis of principles over strict or often shystery interpretation of the law used by his court opponents.
One episode I distinctly remember is the one that involves a leader of an American neo-Nazi organization who organized a counter-demonstration to a Jewish rally or parade. Dressed in what looked like approximations of Sturmabteilung ("shock troops" or SA)uniforms, they peacefully stood on the sidewalks and shouted "Hitler had the right idea" repeatedly. They got arrested and charged with something in court. The Preston father and son lawyer team had the rather unpleasant but legally correct task of defending the neo-Nazi leader on the grounds of freedom of speech.