Article 5

The widespread or systematic practice of enforced disappearance constitutes a crime against humanity as defined in applicable international law and shall attract the consequences provided for under such applicable international law.

But it would only apply to disappearances that took place after the treaty came into effect.  Which makes it a ban on future disappearances, but not applicable to past ones.

The fact that the Bush administration is worried about this is a sign that they don't intend to stop what they're doing.

But we already knew that....