Q: My elderly father has Alzheimer's disease and can't make rational decisions. He never named a power of attorney. Is it too late?
A: A diagnosis of Alzheimer's Disease, by itself, does not mean that a person no longer has the capacity to make rational decisions. However, if your father has had the disease for some time, and it has progressed to the point that he is actually unable to understand the basic concept of giving you the right to make his financial decisions, it is indeed too late to have him sign anything.
A durable power of attorney for finances is a sweeping and powerful legal document that gives the agent unlimited power over the elder's money. It can lead to financial abuse and outright theft of an elder's funds and property when in the wrong hands. Therefore, the law requires that the elder be able to understand what he is giving up in appointing someone to act on his behalf for all money matters.
To get a person to sign any legal document when he doesn't have the mental capacity to do so is illegal and could be considered a crime, depending on the circumstances. If you aren't sure if your father has enough mental capacity to understand a power of attorney, it is best to get legal advice and to have him evaluated by a qualified physician to make that determination. If the physician says he's not competent to make these decisions, then you can't get him to sign the power of attorney.
Your only other legal option is more expensive and time consuming. It is to have the doctor declare your father incompetent, and ask the court, with an attorney's help, to have yourself appointed as the guardian or conservator over him.