Before every gets up in arms about this, consider the world in which we live first.
We live in a world where a foreign power invaded our soil, captured our capital and burnt it to the ground, and we did not suspend our Constitution to deal with the threat.
We live in a world where an internal faction, in rebellion, threatened to end our existence as a country, and we did not suspend our Constitution to deal with the threat*
We have increasingly abandoned that ideal in favor of "the Constitution is not a suicide pact", but we have faced existential threats before and survived them.
So I, personally, need a stronger argument than "there are threats out there".
* Lincoln did suspend habeas corpus, and legal scholars can argue over whether it was done in the proper form, but the Constitution does permit the suspension in times of rebellion.
> Lincoln did suspend habeas corpus, and legal scholars can argue over whether it was done in the proper form
There's not really much debate on the matter -- from the contemporary decision in Ex Parte Merryman and the numerous other district court and circuit court decisions finding against the suspension until it was abandoned up through a chain of decisions repeating its logic (the most notable recent example being Hamdi v. Rumsfeld), the pretty clear weight of decisions from the courts -- and there's not a whole lot of contrary scholarship -- has been that, to the extent that the writ can be suspended, it can't be suspended unilaterally by the executive branch.
> the Constitution does permit the suspension in times of rebellion.
Actually, the Constitution does not expressly permit the suspension of habeas corpus in any circumstances, it (in Art. I, Sec. 9, among limits on Congress' powers) prohibits the suspension of the writ of it with some exceptions to the prohibition.
We live in a world where a foreign power invaded our soil, captured our capital and burnt it to the ground, and we did not suspend our Constitution to deal with the threat.
We live in a world where an internal faction, in rebellion, threatened to end our existence as a country, and we did not suspend our Constitution to deal with the threat*
We have increasingly abandoned that ideal in favor of "the Constitution is not a suicide pact", but we have faced existential threats before and survived them.
So I, personally, need a stronger argument than "there are threats out there".
* Lincoln did suspend habeas corpus, and legal scholars can argue over whether it was done in the proper form, but the Constitution does permit the suspension in times of rebellion.