This quote of course comes from Chapter Eight, which details the trial of Justine for the supposed murder of Victor's younger brother. What is key to realise about this chapter is the way that the inhumanity and injustice of man is explored. In spite of Justine's obvious innocence, the way that the judges, the system of law and justice and the bystanders treat her shows humanity to be bloodthirsty, fickle and violent. She is "execrated" by the bystanders that come to watch her trial and sentence as if it were an entertainment. Even the attempt of Elizabeth to testify to Justine's good character rather backfires, as is shown in the following quote:
A murmur of approbation followed Elizabeth's simple and powerful appeal; but it was excited by her generous interference, and not in favour of poor Justine, on whom the public indignation was turned with renewed violence, charging her with the blackest ingratitude.
Again and again, this incident testifies to the inhumanity of man. What is important to note is the way this links in to a vital theme of the novel, which is the presentation of the creature himself. He starts off innocent and wanting a relationship with his maker. It is the way that he is shunned by his maker and by humanity and treated cruelly that forces him into cruelty, but this cruelty is only paralleled by the monstrous nature of humanity as displayed in incidents such as the trial of Justine. We cannot expect the creature to be good when he has no model of goodness on which he can base his behaviour.