"See here, Captain Crocker, we'll do this in due form of law. You are the prisoner. Watson, you are a British jury, and I never met a man who was more eminently fitted to represent one. I am the judge." (Abbey Grange.167)
In a major scene, Holmes actually plays judge and Watson plays jury for a man; they declare him "not guilty." The roles Holmes and Watson adopt here also tell us a lot about their characters. Holmes is the guy in charge and Watson is a sort of representative of the "everyman."