Students in the U.S. are taught about how the U.S. Constitution establishes three “co-equal” branches of government, Legislative, Executive, and Judicial, with transparency and accountability to voters being essential to each. What we don’t get taught is how a fourth branch has grown and emerged in the 60+ years since World War II and the rise of the military-industrial complex. That complex of which Eisenhower warned, has grown enormously since events of 9/11/01. What now exists is essentially a fourth branch of government that is not only not accountable to the people, but is not even visible to them. We, the people, see only the tips of the complex in the physical pat-downs and naked-body scanners at airports. It is far more extensive than that. Any discussion of modern day political economy or government budget priorities must take this fourth branch into account. Unfortunately, in our political rhetoric it now appears that this top-secret security complex is the new “untouchable third rail” of politics, replacing Social Security.
The Washington Post has created an excellent mix of videos, articles, data, graphs, and maps describing this complex. It is an excellent research resource for students. You can find it here.
I normally try to keep my posts to economics topics. But sometimes the political overlaps the economic. In recent weeks there’s been a large fuss about full-body scanners and intrusive “pat-downs” by TSA agents at major airports. I won’t comment too much about this, but I will note two things. First, the former Secretary of Homeland Security, Michael Chertoff benefits directly from the sale, installation, and use of these scanners. From Wikipedia:
Body Scanners and Conflict of Interest
Chertoff has been an advocate of full body scanners at airports. In 2010 it emerged that Rapiscan Systems, a manufacturer of this technology, was a client of his security consulting firm, the Chertoff Group. He has come under a lot of pressure from fellow republicans for alleged corruption in that he was profiting from the sale of security equipment, which he advocated for, while Secretary of Homeland Security during the Bush presidency. 
This is precisely the type of conflict of interest and intermingling of industrial interests with government military/security interests that we were warned against 50 years ago by President Eisenhower. His speech at that time is worth reviewing: (note for my younger readers who may not have studied World War II close enough – Eisenhower was not only President from 1953-1961, but he was also the commanding general for Allied forces on D-Day in World War II)