The terror of the state in the interest of "the greater good"

 In one of the most striking experiments in an all powerful, centrally planned government, the GDR (German Democratic Republic) existed for nearly 40 years and increasingly terrorized it's citizens.  One of the most feared notorious departments was the Ministry of State Security (Ministerium für Staatssicherheit).  The Stasi in addition to documenting a GDR resident's every move, conducted assassinations of both citizens and non citizens of the GDR around the world.  The terror of the Stasi's prisoners can be felt from a sign to political prisoners of the Cottbus prison that said: "You are worse than a child abuser and you are here to be broken."  Anyone who lived through that period of time remembers the stories of the victims of the state.  Horrors of the Stasi   Why Berlin Cannot Forget the Stasi

The East started with an open border, that is, until the state realized that it was losing it's people to the West.  The East put up a wall to keep it's necessary people inside and promised death to anyone who would try to leave, all in the interests of the greater good, founded in good intentions. 

That begs the point, what can we learn from these peoples' suffering?  How can we prevent such a situation at home?  We must establish constraints and limits of state power.  We must not allow a bureaucracy of secrets become all powerful in the interests of "the greater good", "state security" or "the war on terror".  After all, we humans have had the same weaknesses, biases and temptations since the beginning of time.  But, you might say, the East Germans are different, that couldn't possibly happen here.  Unfortunately it has been proven through numerous studies of how normal people can be made to do terrible things to others such as in the case of the Stanford prison experiment where normal college students posing as guards became sadistic tyrants, and in the Milgram experiment where individuals were instructed by an authority figure to subject a third party victim to painful electric shocks.  To think our state security construct couldn't "go there" is beyond naive, and downright dangerous.  

Meanwhile, the department of Homeland Security, the TSA, CBP, et al are given greater and greater powers of enforcement, surveillance, and constitutional work-arounds in the interests of "border protection", and fighting the perpetual "war on terror".