The greatest good, for the greatest number of people, is always to protect and defend the rights of the individual - because the individual is each and every one of us.
Once we decide to hand the higher power to some entity, to void this or that right of this or that person in cases where they determine it's justified (for national security or whatever), once we make that the acceptable expectation, then for all intents and purposes it is justified in every case. They are now allowed to make that call, they don't have to tell you or anyone else why - especially since it's a matter of national security.
Who do you trust that much, to tell you "Sorry! We declared you [ and anyone else we want ] void for a good cause"?
Set up the expectation to where you have certain rights, and we all do, and these rights cannot be abridged without due process. If you set up the expectation to be: "go ahead, void a person's rights if you really need to, when you see it's necessary to serve the greater good" - well, don't ask for an investigation after they pick YOU to void.
This isn't about excoriating the people who make the tough calls in a crisis. Sometimes bad shit goes down, and somebody has to make a call where people are going to die either way. Shit happens, and the actions taken are investigated after the fact. All factors are judged and determined as to whether what was done was right. When the world goes wrong, the aftermath can be messy - but it's better to have rights that are worth wringing hands over, than to walk around on an everyday basis saying, "my rights are subject to arbitrary suspension and that's fine - this makes me safer!" It doesn't make you safer. It puts us all in jeopardy.
Protect everyone by keeping your rights intact! Trust me, if a situation develops where the government has to accidentally squash you on the way to a terrorist, if it's a case of where they shouldn'ta done that, but it was a regrettable casualty that saved lives, it'll all come out in the wash. You don't have to give up your rights beforehand to be declared regrettable collateral damage after the fact. But when we start saying up front "rights are expendable" - when we make that the acceptable expectation - then they're all going to erode and dissolve and be washed away. Right straight down the toilet, and not just in extreme cases where a tough call had to be made.
It will be an easy call.