I don't think there's any situation where it can be legally justified. I think it can at least theoretically be justified on moral grounds in some circumstances, and in those circumstances the torturer should be willing to pay whatever penalty is deemed appropriate. After all, if the information he seeks is that overwhelmingly important, then he should be willing to pay a price for obtaining it. If the torturer is not willing to sacrifice hiimself for the information, if he is only willing to sacrifice his victim, then how important can the information possibly be? Be realistic, the nature of government is to stretch its limits, so one can't reasonably expect legalized torture to remain within the nuanced strictures its defenders envision for long. [Source]
If torture were morally positive or neutral, there would not be such a feverish attempt to justify it in such a narrow, concise set of situations. It's precisely because we instinctively know that torture has an inherent sadism to it, and that sadism is at all times and in all places depraved that causes those who defend torture in limited circumstances to squirm. Additionally, if it were morally neutral like firearms, the defenders would not have to resort to esoteric situations where the consequences are so drastic that the normal laws don't apply, but could rather point to a host of morally positive situations wherein torture was used for a clear good.
Those who break reasonable laws and moral norms should always expect to be punished if caught, and that includes torturers. If a soldier tortures a man who turns out to have critical informated needed to prevent a major terrorist attack, then that might warrant leniency in the sentencing of the soldier since the outcome was good and the target guilty of conspiracy. However, neither of those factors can go beyond modest mitigation into outright amnesty for the torturer for an objectively evil act.
Torture is also a lot like vigilantism in that it is pre-emptive and error-prone. Like vigilantes, torturers do not have a moral excuse from justice because they thought they had the right person. When they get the wrong person, and they almost always do, whatever grievances they thought they had do not warrant mercy on the part of the court toward them. No matter how heinous the alleged offense, their victim is objectively innocent, and they are objectively guilty, and even worse, they did not even give the objectively innocent party an opportunity to prove their innocence. Accordingly, both groups then, in that situation deserve to have the book thrown at them by society, and have no right to expect an ounce of leniency when they get the wrong person, be that person innocent or insufficiently related to the crime.
Of course the legality argument is one of tautology. ANYTHING can be made legal with the stroke of a pen.
I think what Vox meant to say was that one cannot justify a legitimate legal case for it. There really isn't a legitimate case to be made there, since torture is naturally a horrific violent crime.
A case cannot be made for it now because it is indeed against our laws. and therefore a legal claim cannot be made to support it. But if it gets redefined or relegislated, then the arguments in favor of it will also be obvious. As with any legal argument, it depends entirely on what the current law is.