For example, suppose you're heading an FBI group, and you've got a suicidal terrorist in custody who is part of a plot to detonate a nuclear bomb in LA. You have excellent evidence this guy is involved, and that the terrorists probably have a nuclear bomb in the country, and, if they realize their coconspirator has been captured, they are likely to detonate immediately.
The terrorist demands to see his lawyer. Your specialists say you should deny that request, because his lawyer may signal, intentionally or otherwise, the other terrorists. Should you allow the terrorist to meet with his lawyer?
Our society's laws say he should be able to see his lawyer. We value that kind of thing. And yet, if you would risk millions of lives to protect this right... Well, that seems perverse to me.