How in the world can you know he wrote it? Maybe he just signed his name to it? It seems to be all the left is about - faking.
The book is a 400 page hornbook with extensive citations to Supreme Court cases. I doubt someone else would allow him to take the credit for such a treatise if he didnt write it.
And the few interviews i have seen of him confirm his extensive knowledge of constitutional law. The good thing about the book is that it isn’t a leftist treatise as much as it is a legal analysis of case law.