What surprised you in writing this book?
What surprised me is how much of our constitutional law has been the result of trial and error—what works and what doesn't. What are the lessons of the past? Slavery was a mistake, segregation was a mistake. And a lot of our constitutional law is a result of saying, "We've made some mistakes; let's learn from them."
How do you think this book will surprise readers?
Readers might be surprised by how many of the things that we take to be the heart and soul of our Constitution are either not clearly in the text or were not thought to be very important when the Constitution was drafted. When we think of the Constitution today, we think of things like robust freedom of speech or that you can't discriminate on the basis of race or sex. But it's very hard to find those in the text of the Constitution, and there's evidence that the people who adopted it did not think they were enshrining those principles.
What lessons can conservative justices like Scalia or Thomas take from this book?
I don't think this approach—that the Constitution is a matter of evolving precedents and traditions—is conservative or liberal. I think it actually describes what judges on both sides of the political spectrum actually do.
What ramifications does a living Constitution have for combating terrorism?
At this point, it is very hard to know. Some of them might be lessons that we need more government power, and some of them might be lessons that we need more checks on the government. I think that's going to be a real task not just for the courts, but for the government and really every citizen to figure out over the next decade or so. But the way to figure it out is the way we figured out other problems, which is to say what works and what mistakes have we made, rather than try to ask the question: What would the people who sat in Philadelphia in 1787 have wanted to do about al Qaeda? That is not a very useful question to ask.