The Anchoress wrote a rather speculative but fascinating piece, wherein she wonders if America is being ripened for a coup. Such concerns seem a little premature to me, but not wrong – we’d like to think America somehow immune to the forces that brought down empire after empire, that History has ended, after all, and there’s just no room for America to descend into the control of those conjoined twins, anarchy and tyranny.
Why not? What forces will keep history from repeating itself? Progress? OooHaa! Think I just dislocated my knee by slapping it!
Anyway, my thoughts, as posted in a comment to the above-linked piece: 
I suggest that the tipping point is the establishment of the Praetorian Guard. It has been plausibly suggested that the IRS, in the ancient, unbroken tradition of court hangers-on, didn’t need anybody to tell them that they should suppress the get-out-the-vote campaign by thwarting the applications for non-profit status of politically conservative groups. It was simple enlightened self interest to do so.
Tacitus tells us how Sejanus, an up and comer, worked his way into Tiberius’s confidence and ended up as head of the Praetorian Guard, and was planning to take over when Tiberius died, and eventuality Sejanus himself might facilitate.
The telling part of the story: Tiberius, when he began to grow suspicious, did not call out Sejanus directly, or attempt to send – who else? – the Praetorian Guard to kill him. Nope – he knew how things worked. He sowed confusion by a series of letters to the Senate, so that no one would know where things stood – Romans, not being dummies and having seen how fast the political winds could change, quickly became neutral toward Sejanus. Popular support having been neutralized, Tiberius secretly appointed another up and comer, Marco, head of the Praetorian Guard, and called Sejanus to the Senate by letter, ostensibly to receive an honor. Then, as another long and meandering letter was read, supporters of the Emperor surrounded the Senate, and the letter, at the end, suddenly changed course and condemned Sejanus. Marco’s forces seized him to his unhappy end.
But: this event made clear to the Praetorian Guard who wielded the real power in the Empire. They then made sure that only emperors to their liking ever came to power, and promptly disposed of those who displeased them.
Is the IRS coming to appreciate its role in determining who gets to be President? Or viewed more generally, if trends continue, there will soon be enough government workers so that government workers in general can simply choose who gets to be President, if they wish, by simple exercise of democracy.
These concerns do not require any conspiracy theory. They spring from having a toehold in history.
Yard Sale of the Mind 