> "Never again" like Nazi Germany? "Never again", like having people arrested at night by the Gestapo and held without warrant, charge or lawyer? "Never again", like having people spy on each other (and the state spy on everyone) who might a dissident? "Never again", like profiling people by religion, race or origin?
Actually, exactly like that.
It is impossible to put policies and rules in place that will prevent these sorts of things from happening in any country in the world at any time in the future.
It's even impossible to prevent these sorts of things from being done in the United States (and I'm not talking the anti-terrorism policies and actions here, I'm talking about things as simple as misbehaving law enforcement agencies)
All that can be done is to make this sort of thing unacceptable and punish people who misbehave (and since this happens after the fact, it doesn't prevent it from happening)