No doubt in every country, some things cannot be questioned. In the United Kingdom, where I live, you cannot really question the continuation of the Monarchy without making yourself an Outsider on whom, quite probably, a file will be opened somewhere. In the United States, you cannot question the Constitution - even though it has been amended from time to time. If you said that the Constitution is at the root of many of America's most profound problems, you would certainly be put on someone's List.
And yet not a month goes by without it being obvious to the rest of the world that the Separation of Powers and Checks & Balances enshrined in the Constitution as they work out in practice paralyse American government, both Federal and State. It creates a system which is weak and wide-open to corruption. It ensures that major problems are left untackled, often for decades. It fails to provide citizens with basic securities, so much so that many of them think that the solution is individual gun ownership - something you would only expect to encounter in a lawless third world failed state.
Tim Weiner constructs his book around the theme of the perceived and perennial conflict between the preservation of liberty and the construction of security, fudged over decades by Presidents and the FBI by simply doing things illegally and off the books. Edgar Hoover perfected the system, keeping the records of illegal operations in a personal system "Not For Filing" which meant that the operations were neither indexed or retrievable in the FBIs archives.
It's a sorry tale, told chronologically and generally in thumbnail narratives some of which are abandoned inconclusively. As a result, it's not particularly readable. There are partial narratives some of which are very interesting. For example, American anti-Communism does not begin with the Cold War. It dates back to the Russian Revolution itself and it shaped J Edgar Hoover's thinking and policies right from the beginning of his career after the First World War. It continued to shape the FBIs thinking to the point of ultimate absurdity when student movements in the 1960s and 1970s were perceived as Communist front organisations.
More generally, there are constant reminders throughout the book about the ignorance and cultural isolation of Americans: they don't know geography or history or foreign languages. They simply don't understand the rest of the world. The surveillance may be awesome and cost megabucks; the briefings fed to the President are often pitiful.
But I read the background narrative in the whole book as the tragedy of the Constitution which nowadays yields a Congress of paid lobbyists and headline-grabbing nutters, a Supreme Court which can never really make up its mind, and Presidents who are sometimes able but thwarted in their attempts to tackle the major problems America faces - and sometimes stupid and simply unable to recognise the existence of those problems. The American Constitution nowadays is malware which infects and paralyses the whole society.