What's the difference pf the court where Tom was tried and the secret courts of men's hearts?

In a court of law, the jury has found Tom Robinson guilty of the rape and assault of Mayella Ewell. It's a blatant miscarriage of justice, one that completely ignores the inconsistencies and contradictions at the heart of the prosecution case. In truth, however, the jury's verdict has nothing to do with justice, but everything to do with maintaining a system of white supremacy and keeping African-Americans "in their place."
The twelve members of the (all white) jury found Tom guilty in the secret courts of their hearts before they found him guilty in a court of law. In fact, they found him guilty before they even set foot inside the courtroom. In other words, their racial prejudice went so deep inside them that, as soon as Mayella Ewell accused Tom of raping her, he was a dead man walking. Atticus could try his hardest to convince the jurors to find Tom not guilty in a court of law, but there was absolutely nothing he could do to change the verdict that they'd already reached in the secret courts of their hearts.