Nicodemus reappears among the rulers and asks, 'Doth our law judge any man, before it hear him, and know what he doeth?' He does not yet offer a full confession of Jesus; he asks for fair procedure.
His colleagues respond by asking whether he too is from Galilee and telling him to search the Scriptures.
Torah repeatedly values truthful testimony and impartial judgment, and a person should not be condemned without establishing the matter. Nicodemus' appeal fits that broad legal ethic without requiring that John be quoting a single technical statute. The answer he receives is ad hominem and geographical: Galilee is invoked dismissively.
The claim that no prophet arises from Galilee is itself problematic, since 2 Kings locates Jonah at Gath-hepher in Galilee.
The exchange illustrates how procedural fairness can disappear when a conclusion has already hardened. Nicodemus asks that Jesus be heard before judgment; his colleagues answer by questioning Nicodemus' associations.
John's irony is especially sharp because the men who tell Nicodemus to 'search' speak too confidently about biblical geography.