Powers of attorney are legal documents that must comply with specific laws in place in every state. Who has to sign a power of attorney differs depending on various factors, as power of attorney laws differ among states, and some states have different laws that apply to different kinds of powers of attorney. Always talk to a lawyer if you need legal advice about signing a power of attorney.
Powers of attorney can only be conveyed through writing. All states require that the principal, the person granting the decision-making abilities, must sign the power of attorney document. If a principal is not physically capable of signing, she can have someone else sign the document on her behalf. However, a principal who is mentally incapable of making decisions may not direct someone else to sign the power of attorney. Only a principal who is of sound mind and who can make her own decisions is capable of passing on power of attorney.
It isn't always necessary for an agent to sign a power of attorney, though the agent's signature will not invalidate the document. Many powers of attorney include multiple or alternate agents, or appoint organizations as the attorney-in-fact. These agents, or representatives of the organization granted power of attorney, can sign the document in any manner as required by the principal. Alternate agents may also be required to sign under the terms of the power of attorney document.
Some states require that certain powers of attorney be signed by witnesses. Some states, for example, require that health-care powers of attorney and other advance directives have at least one witness sign the document before it can be effective. For instance, the principal and at least one competent witness must sign an Arizona health-care power of attorney, while the principal and two witnesses must sign powers of attorney for health care in Delaware.
Some states also require that powers of attorney be notarized. Even if state law does not require it, powers of attorney can be notarized without invalidating the document. For example, Hawaii requires that powers of attorney for health care be signed by at least two witnesses; but if the principal notarizes the document, the witness requirements are waived and notarization is sufficient. Tennessee, on the other hand, requires two witnesses for a power of attorney for health care, with optional notarization.