That is certainly one kind of tyranny and there are others. In terms of relative danger presented by prosecutorial misconduct I would rate top down tyranny as far more dangerous. We see this every day in the Obama administration. It can include selective disregard of the whistleblower protection; it can include selective enforcement against guitar companies for the kind of wood they use; it can include the railroading back to jail on alleged parole violations for a purely political propaganda motive about a video; it can include enforcement of campaign contribution laws selectively and arbitrarily against filmmakers critical of the Obama administration; it can include threats of prosecution against bankers for "excessive" emoluments to CEOs.
The list is very long when one reviews the top down prosecutorial malfeasance of this administration.
There is also prosecutorial misfeasance which is not top-down but which is very pernicious to those against whom it might be directed such as Zimmerman. Prosecutions which are incited by the mob are terribly dangerous to liberty but not nearly as frightening as the top down variety.
There is also corruption which we have seen forever especially in times like prohibition. In most parts of the world if traffic cop stops you, you are expected on the spot to pay your bribe. When that becomes institutionalized, as it was for example in the Soviet Union, the whole rule of law breaks down.
Ultimately, it's a question of culture because ultimately the law, just like politics, will reflect the culture. If we institutionalize relativism through our educational system we should not be surprised if it creeps into our legal system. The problem is not to confuse relativism with due process.
