The trial is perhaps the most crucial scene in the play. In Act IV, Scene I, Shylock demands the right to cut a pound of flesh from Antonio’s body. The court’s decision determines Antonio’s fate. The duke appeals to Shylock’s sense of compassion, to no avail. Shylock says he will stick to his promise: “And by our holy Sabbath have I sworn / To have the due and forfeit of my bond.” Antonio has willingly signed an agreement to allow Shylock a pound of his flesh if he did not repay Shylock on time.
The duke believes there is nothing to be done. Bassanio attempts to offer money, which Shylock refuses. Antonio’s friends hurl insults at Shylock and cry for their friend, but Shylock does not yield. Portia, disguised as a lawyer, arrives and describes to Shylock the wonders of mercy: “it is twice blest; / It blesseth him that gives and him that takes.” She declines to simply pardon Antonio because that will set a flawed precedent.
Portia eventually manages to find a loophole in Shylock’s argument. The bond does not make allowance for any blood to be spilled: “Shed thou no blood, nor cut thou less nor more / But just a pound of flesh.” He has insisted on his bond and therefore cannot legally back down. On top of that, there is a law “against an alien” seeking “the life of any citizen,” on pain of death and confiscation of his money. The duke forgives Shylock of his life, and Antonio allows for Shylock to keep one half of his goods. The condition is that his money goes to Shylock’s daughter and her Christian husband after his death and that Shylock convert to Christianity.
The scene concludes with the disguised Portia insisting that Bassanio give her a ring as payment. This is the ring she gave Bassanio as his wife and insisted he never remove. He eventually does so, which leads to more teasing in the play’s conclusion. As you can see, the trial scene affects everyone. Portia displays her intelligence and saves her husband’s friend, Bassanio’s mind is set at ease (though his marriage might be at risk), Antonio’s life is saved, and Shylock is threatened and humiliated.