A personal care facility will not allow my mother to leave the facility because she is behind on her payment. Is this legal?

One thing I always do when I have a question about the law is that I contact several lawyers in that particular area and I ask for a phone consultation which is extremely helpful. Because you don't have a lot of time with them, I prepare my questions ahead of time in a spiral notebook and number the questions, so each lawyer I talk to - I only have to reference the number to the question being answered instead of re-writing the question.

Review the contract immediately and contact the Center of Aging directly. I do not believe this is legal, if necessary you can have a police escort to go and retrieve her. Ask the question, have they taken guardianship of her because she did not have the proper paperwork in place already, such as Healthcare POA or POA. This would be the only way I could see them keeping her and perhaps they did not inform family when they took guardianship but very unlikely. Don't leave her there is she doesn't want to be there.

Something doesn't sound right here. Find out what the law is in this instance. If she signed a contract, what does it say.
Personallly, I don't think anyone can force her to go back for any reason. It's not a prison, and she doesn't have an ankle bracelet does she? Talk to a lawyer who deals with elder law. It will cost you a little money, most likely, but it will resolve the situation so that you know what you can do legally.
Continuing to stay there is going to run up the bill even more, making the situation even worse.

This sounds like a violation of her civil rights. Debtors prisons were abolished in our country, and that is what the situation sounds like. If she lives with you, perhaps you and your mother in law can set up a repayment plan with the facility from the money she will save. Talk to the ACLU and ask for legal help. I hope things change soon. Rebecca

The Facility is saying is The Agency of Aging that is not letting her leave the center, their answer to me is they are afraid if she goes out for a visit, she will not want to return to the facility and they will have to get law enforcement involved to return her to the facility within 24 hours, which I think is unjust. I believe it's all because she owes the facility a substantial amount of money.

Who is not allowing her to go out? The agency on aging or the care center? On what grounds? Have you seen the contract under which she is living there?