If your father is unable to make medical decisions for himself, than his agent under his medical power of attorney has the authority to do so. You say you are the agent. In that case, you would have the authority to decide where he receives treatment. However, the nursing home and doctor have the obligation to determine your father is released into a safe situation. I suggest that before you assert any legal rights you have you first discuss the matter with the nursing home's ombusman. Every nursing home in Colorado has one. The role of the ombudsman is to help facilitate communication between the residents/family and the facility administration. In the end, though, the nursing home cannot keep your father against his will, and if he can't express his will they can't keep him against the will of his appointed agent.