In chapter 14, Jem tells Scout to stop antagonizing her aunt Alexandra because it just causes more contention in the house. Jem even says that he will spank her if she does it again. This drives Scout to the point of physically lashing out at Jem and Atticus goes in to break it up. He asks who started it and Scout says the following:

"Jem did. He was tryin' to tell me what to do. I don't have to mind him now, do I?" (138).

Poor Scout. She has to obey so many people in her life: Calpurnia, Atticus, Aunt Alexandra, and now Jem! Life is pretty crazy since the trial of Tom Robinson is just around the corner. Jem was trying to help Scout not cause any other trouble, but he lacks the parental experience and authority to do it correctly. Atticus, being the compassionate and wise father that he is has the best response for Scout:

"Let's leave it at this: you mind Jem whenever he can make you. Fair enough?"(138).

Could it get any more ambiguous than that? Does it seem that Atticus is saying that if Jem can physically make her obey, then she will have to? Or, is he simply distracting Scout so it can be called up for discussion at another time? Either way, it leaves the situation up to Jem and Scout to resolve on their own when the time comes. Ultimately though, the compromise is that Atticus won't actually say Scout must mind Jem unless Jem can figure out a way make her mind.