I tried to look at both sides of the argument and I just can't help but feel like Portia is trapping Shylock. I know she tries to give him a chance to do the right thing by reminding Shylock that Bassanio has three times the original amount Antonio agreed to give him: "Be Merciful. Take thrice the money. Bid me tear the bond." But Shylock is so set on his revenge that he is blinded to reason and compassion. He has been kicked around all his life and things are finally looking up for him. He's smug and over confident, telling the judge she is sound and intelligent. I think by doing this he may have even ticked Portia off. She doesn't need a Jew to tell her she's intelligent. Then she asks if Shylock had a doctor for Antonio and when he said it wasn't stated in the bond, she basically lost it. She then uses these quotes he told her to put him in a corner for the rest of the trial, "The bond doth give thee here no jot of blood," "But just a pound of flesh. If thou tak'st more or less than just a pound...thou diest, and all they goods confiscate." She then baits him, saying "Why doth the Jew pause? Take thy forfieiture," and when Shylock sees the error of his ways (basically learning his lesson) and instead asks just for the money, Portia won't let him have it. He didn't even ask for the larger sum, just the original amount, at least what I think he is asking for. Though Portia did give him a chance to right his wrong at the beginning, she shouldn't have taken advantage of him like that. She probably knew the law inside and out whereas Shylock seemed to not really understand it at all. It just wasn't a fair fight.

*Tina