Judith Merrill is expected to be held (assuming she sticks to her guns) until the term of the investigating grand jury she's supposed to talk to expires, or until the judge determines that she isn't going to talk. This bizarreness comes about because the official legal justification for her imprisonment is not to punish her, but to coerce her into talking. When the grand jury's mandate expires, it doesn't matter if she talks or not, so there is no need to coerce her, and if the judge in his wisdom determines it won't do any good, he's supposed to let her go.
I naively believed that our authority to put people in jail was supposed to be limited to punishing people who had been found guilty of crimes they had committed. Our government's authority to coerce us into doing things we don't want to is supposed to rest on defining failure to do what the government wants us to do as a crime, and if we don't, finding us guilty of that crime by due process of law. It is explicitly illegal for the government to put you in jail for something they believe you are going to do -- "prior restraint" -- unless they can show that you've actually committed a crime. Thus, I find it bizarre and frankly rather scary to discover that the courts claim the explicit right to affirmatively force a person to do their bidding, as opposed to finding her guilty of failing to do so after the fact, and the scariness is multiplied by the fact that they can deprive that person of liberty in that forcing with rather less due process of law than would be required to punish her for a crime. And apparently the only reason that the term of detention is limited is a lack of will to circumvent a requirement that comes about by coincidence -- I don't know of any reason why a grand jury has to have a time limit, and certainly nothing prevents another grand jury from demanding the same evidence.
You don't have to be a terrorism suspect to be detained indefinitely without trial or charge. All it takes is to be an ethical journalist with the guts to stand by your promises. Doesn't that make you feel safe, secure, and full of civic pride?