In chapter 25 Scout compares the court that Tom was tried in and "the secret courts of the men's hearts". In what way are hearts like courts?...

Think about the deeper meanings and proceedings in a court.  There is much debate that goes on inside the courtroom (as well as in someone's heart).  There is rarely clear-cut evidence, so the people involved much search their hearts and go with what they truly feel is right.  The jurors have to live with the decisions they make, especially the jurors in this case--something that will stick in their hearts for a long time.  Remember, the verdict was definitely not a unanimous decision. Decisions are made both in a court and in your heart.

If your teacher appreciates a sense of humor, you can be a bit more tongue in cheek, too, by including a pun on the fact that a court has chambers and a heart does as well.