So what is it about? Near the end Sean writes that:
scholars of all stripes in the American academy [are] suggesting to one another that the "true meaning of the law" is found in the secrets one can unearth about historical lives, debates, speeches, and so forth ... I wrote this book because I desperately wanted to see this conversation end.He's unlikely to get his wish, but he presents a good case. It's unlikely to work because one book rarely silences a whole crowd, and because I think to have any chance of doing this he would have to engage in more detail and at greater length with his opponents than he does here. Perhaps he'll write a sequel that does that.
He rejects the idea that the US Constitution means what its framers had in mind when they wrote it on the grounds that we can't know what they were thinking, they may have been thinking different things, and it makes more sense to be guided by what they wrote and agreed on than by what they were thinking as they did so. He rejects the idea that it means what it meant when it was framed on the grounds, roughly, that it doesn't say so but, on the contrary, is written in ordinary language and so, presumably, has a non-technical, hence non-rigid, hence flexible meaning. The Second Amendment might provide a useful example. It would be silly to take the "right to bear arms" to refer to a right to carry only muskets and the like on the grounds that this is what "arms" meant to the people of 1791. (It wouldn't necessarily be silly to argue that we should interpret it this way in order to protect lives, but it would be silly to think that this is the only correct interpretation regardless of the consequences.) Similarly, Sean argues, it is silly to think that we should take words like 'equality,' 'citizen,' and 'cruel and unusual' as meaning only exactly what they meant (designated, referred to) to people in the United States in the late 18th century.
History matters to constitutional interpretation only in the sense that if, say, the word 'arms' ceased to mean weapons at all then we would have to bear in mind that it did mean weapons, and not just limbs, in 1791. I think Sean acknowledges this point in his Twist example on p. 193, but he doesn't spend a long time on it. So history does matter, but it isn't the only thing that matters. Because the Constitution lacks much definition and technical language, it is open to interpretation. Which interpretation is correct? In a sense the answer is none. To think otherwise would be to pretend that the openness or flexibility is not there. But the best interpretation will be, Sean argues, the one that both makes a proper use of the words of the text and provides the best and most coherent account of the ideas contained in the document. I'm no expert, but this all sounds about right to me.