The main difficulty I have with his commentary is this. I can imagine a critic — Green’s dialectical opposite, Maur Red — saying, “Look, okay, so the US is a borderline case of law. Who cares? It’s still law.” If asked to clarify, Red could say: “What’s at stake here is not whether US law is a form of law, but whether or not it is an exemplar, an instance of the focal meaning of law. These are different issues.“
As I imagine the conversation going, I think Red could then chastize Green for overspeaking when he claims that this entails that US law is not “actually” law, because nothing at all follows from concluding that US law is a borderline case of law. For that is apparently no more defensible than saying, e.g., that penguins are not really birds, given that penguins are a borderline case of birds, or that the half-competent doctor is not really a doctor, given that the doctor qua doctor makes no errors.
What Green should say, instead, is that US law is on the verge of being a near-miss case of law, which is a special kind of borderline case. And Red might concede that that would be worrisome. But then, he might conclude, you cannot infer that something is a near-miss case of law just because you deny that it has the qualities of an exemplar case, any more than you can infer “penguins are not birds” from “penguins are not robins or bluejays (etc.)” Only some borderline cases are near-misses. Others are just odd, ironic, or unexpected.