"It hasn't been a conscious decision. [...] Members of Congress are generalists and need to defer to experts within the national security realm, as elsewhere."They are particularly concerned about being caught out on a limb having made a wrong judgment about national security and tend, therefore, to defer to experts, who tend to exaggerate threats. The courts similarly tend to defer to the expertise of the network that defines national security policy."The presidency is not a top-down institution, as many people in the public believe, headed by a president who gives orders and causes the bureaucracy to click its heels and salute. National security policy actually bubbles up from within the bureaucracy."Many of the more controversial policies, from the mining of Nicaragua's harbors to the NSA surveillance program, originated within the bureaucracy. John Kerry was not exaggerating when he said that some of those programs are 'on autopilot'."These particular bureaucracies don't set truck widths or determine railroad freight rates. They make nerve-center security decisions that in a democracy can be irreversible, that can close down the marketplace of ideas, and can result in some very dire consequences."I think the American people are deluded...They believe that when they vote for a president or member of Congress or succeed in bringing a case before the courts, that policy is going to change. Now, there are many counter-examples in which these branches do affect policy, as Bagehot predicted there would be. But the larger picture is still true – policy by and large in the national security realm is made by the concealed institutions."