The final part of Act IV is a short comic scene in which Dogberry questions the prisoners, Borachio and Conrad, before the Sexton (the town clerk). Once again, the humor comes from Dogberry using the opposite words or wrong words to describe the illegal activities of the prisoners. When the watchman accuses one of the prisoners of calling Don John a villain, Dogberry calls this an act of "perjury" (line 37). Dogberry should have said slander. Perjury is the act of lying under oath. Slander is a verbal act of insulting someone or making malicious statements about them. Also, when the watchman relates that Borachio received money from Don John for wrongfully accusing Hero, Dogberry calls that "burglary" (line 44). Dogberry should have called that fraud or conspiracy. Burglary, of course, is the act of breaking into a house to steal money or goods. Obviously, that is not what Borachio had done. Dogberry tries to show off by using legal terminology, but he is obviously incompetent. Yet, despite that incompetence, he does somehow manage to get the confession and solve the crime against Hero. Dogberry is perhaps not unlike the inept Inspector Clouseau of the Pink Panther movies. He always does or says the wrong thing, but he succeeds anyway.
The humor of the interrogation scene also comes from Dogberry telling the Sexton to write down irrelevant or unimportant information in his transcript of the questioning. When Dogberry calls the prisoners "knaves" (crafty or tricky villains), Borachio says, "We are none" (lines 25-26). So, Dogberry asks the Sexton, "Have you writ down that they are none?" (28). Dogberry tries to imitate proper legal procedures, but has no idea what he is doing.
At the end of the scene, Conrad calls Dogberry an "ass" (line 66). Dogberry gets angry and launches into a speech about how great and wonderful he is. Dogberry is a comically proud character. Most likely, the members of the audience would agree with Conrad's remark since they would see in Dogberry a similarity to the constables of their own towns.