In another room of Angelo’s house, the Provost appeals to Angelo that he might stay Claudio's execution. Angelo is unmoved, even when the Provost mentions that Juliet is soon due to give birth. A servant brings word that Claudio's sister, a "virtuous maid," has come to see Angelo. Isabella then enters with Lucio. She pleads before Angelo to spare her brother, though she confesses that she is disgusted by Claudio's behavior. A just compromise, Isabella suggests, is to condemn Claudio's fault but not the man himself.
Essentially every character except Angelo is on Claudio’s side, but because Angelo is in the position of power, Claudio’s sentence is unchanged. This is yet another illustration of the dangers of unchecked freedom—in this case, Angelo’s unchecked freedom to discipline others. Isabella is placed in an uncomfortable position by her brother’s actions, and she seeks to carve out a position similar to the one Escalus espouses earlier: to condemn Claudio’s actions as wrong but avoid making an irreversible judgment about him as a human being.
Angelo replies that every fault is condemned before it is committed. However, the actor must be punished. Isabella is distraught, but Lucio quietly counsels her to implore Angelo with more passion. Isabella and Angelo go back and forth several more times, and Lucio again tells Isabella that she is too "cold."
Here, Angelo again displays his faith in the rule of law, which he earlier espoused in Act 2, Scene 1. He shows conviction that justice requires not fair treatment for everyone, but rather that as many people as possible receive punishment for their actions.
Isabella tells Angelo that if Claudio were the one in the position of power, he would take mercy upon an imprisoned Angelo. Angelo continues to dismiss her, but Lucio eggs her on, encouraging her to touch Angelo. She speaks with more passion and implores Angelo more aggressively. Lucio remarks that he is pleased with Isabella's new tack. Finally, Isabella suggests that ignorant, arrogant humans often try to mete out punishments that are better left to divine forces. Both Lucio and the Provost appear heartened that Angelo may be swayed. She tells Angelo that if he senses any guilt in his own heart, he should not carry out Claudio's sentence.
Clearly, Isabella’s point about the fallibility of human justice touches a nerve with Angelo. He seems to be a firm believer that divine commandments can be effectively enforced with earthly laws, but Isabella’s argument to the contrary may be enough to shake his disciplinarian resolve.
This supplication seems to break through to Angelo, and he tells Isabella he will think about her request and bids her to come see him the next day. Isabella agrees to return the next morning, and she leaves with Lucio and the Provost. Once alone, Angelo delivers a soliloquy about his immoral lust for Isabella. He wonders whether it is her virtue that makes him so sexually interested in her, and remarks that "Most dangerous is that temptation that doth goad us on to sin in loving virtue."
After meeting Isabella, Angelo is caught in the paradoxical position of trying to punish a sort of immorality to which he now feels himself succumbing. In this speech, he tries to shift the blame onto Isabella, while maintaining himself as a virtuous figure (an action that is rather common among men in the world, sadly). According to his dubious reasoning, it is his love of virtue that makes him lust for Isabella. Thus, she and her virtuousness are to blame for his inordinate desires, rather than his own lack of self-discipline.