I found the courtroom scene quite unbelievable. The judge hardly asked Ponyboy any questions of relevance to get an indication of whether living with Dally and Soda was a fit residence for the youth. The questions mostly pertained to the incident with the murder. A judge would have actually pried much deeper into what happened. He would have asked some questions to lend background to the murder scene. For example, do you often hang out in the park at midnight? Why were you at the park that night? Those questions would have led to the truth that Dally hit Ponyboy and the judge would quickly remove Ponyboy from the house. That's just the beginning. More questions would have led to information about the rumble and other disparaging truths that Ponyboy's guardian Darry partiicipates in melees alongside his ward. That too would be immediate grounds for removal. I like The Outsiders but at times it is evident a 16 year old wrote the book. The flimsy court scene was certainly one of these instances.
Times have changed. Courts have changed. Laws have changed. As Soda and Pony were living in a household without parents, the primary objective of the hearing was to determine the fate of these young men. The court could quite possibly have been a family court in today's society. Yes it seemed believable.
There are a few things that we need to keep in mind when considering the answer to this question. First, we must remember the time period in which the novel was written. "The Outsiders" was written in the 60's. The court system has changed a great deal between now and then. Also, the juvenile justice system is different from state to state.
Ponyboy was not on trial. Although he ran away with Johnny, he was not responsible for Bob's death. This hearing was more or less to determine what to do about Ponyboy and Sodapop's living situation. In fact, after everyone explained their side of the story, the judge did not find it necessary to ask Ponyboy about what happened the night of the murder.