Tortured Logic

The NY Times recently posted a range of opinions on torture after the report of torture at Guantanamo. I disagreed with much of what Andrew McCarthy had to say (including his definition of what is and is not torture), but the logic of this particularly escapes me:

On that last score, even those of us who have argued that there is a place for enhanced interrogation techniques have insisted that those techniques should be limited to intelligence gathering in dire threat circumstances; they are not for gathering trial evidence. You can call a proceeding in which coerced confessions are used many things; one thing you can’t call it is a “trial.”

Why shouldn't coerced confessions be used in a trial? Besides the obvious reasons of them being biased, fruitless, and, of course, torture?

I would love to know McCarthy's precise reasoning for not wanting coerced confessions used in a trial. I cannot conceive of a reason that could disqualify them from trial proceedings and yet still yield useful intelligence. If you're going to destroy America's reputation by torturing prisoners, you should at least be able to back it up.