Falstaff, Falstaff’s page and Bardolph have arrived at Justice Shallow’s estate in Gloucester where the justice is trying to coax them into staying for dinner while simultaneously attending to details of various legal and financial matters presented to him by his servant Davy. For one of these cases, Davy begs Justice Shallow to rule in favor of his friend William Visor. Justice Shallow protests that Visor is an “arrant knave” with many suits against him, but Davy insists that it doesn’t matter what Visor is, it only matters that Davy, the justice’s loyal servant for eight years, is making a request: “if I cannot once or twice in a quarter bear out a knave against an honest man, I have a very little credit with your Worship,” Davy protests. Justice Shallow agrees to rule in Visor’s favor. Davy exits. Justice Shallow exits, leading Bardolph and Falstaff’s page into the estate.
Justice Shallow’s behavior reveals that he doesn’t possess the Chief Justice’s moral rectitude: whereas the Chief Justice acts according to ethical principles regardless of the parties involved, Justice Shallow allows himself to be persuaded by Davy into favoring the guilty Visor instead of Visor’s innocent victims. The Chief Justice would likewise never agree with Davy’s reasoning that loyal servants deserve immoral favors from their masters.
Alone on stage, Falstaff mocks Justice Shallow. His servants, watching him, become “foolish justices” while he among them becomes “a justice-like servingman.” Falstaff reflects “that either wise bearing or ignorant carriage is caught, as men take diseases, one of another. Therefore let men take heed of their company.” He thinks happily of how he will make Prince Hal buckle with laughter by telling stories about the justice. “O, it is much that a lie with a slight oath” can do, Falstaff observes. Falstaff exits.
Falstaff likens behavior and personality to a kind of disease that is contagious to those around it. With his usual lack of qualms about honesty, Falstaff plans to fudge the details of his account of Justice Shallow (to add “a lie” to the true “oath” of the story) in order to make Prince Hal laugh. Though notice also how much Falstaff seems to care for and love Hal.