Hi there, I would love to give a very straight forward cut and dry response but It varies state by state and there are many aspects involved in a decision like this. In the most general broad scope of things her age(If she is a minor) and her mental state of mind(Is she a danger to herself or others) are two factors that could help to have her committed against her will. First off if she is a minor her parental guardian could have her admitted against her will in most states. Secondly if she is a danger to herself or others she could be admitted to a mental institution against her consent and held for a brief period of time for evaluation however this would not be an admission into a rehab facility so it would probably not be an ideal outcome if rehab is the goal. Hope this helps!