Once your child is 18, he or she is considered an adult in the eyes of the law. You no longer have the right to speak to their doctors. If you are a parent or primary caregiver of a child with developmental disabilities, it is imperative that you file for POWER OF ATTORNEY before the child reaches their eighteenth birthday. You CAN NOT consent to medical procedures for your adult child unless that child signs a power of attorney granting you that right. However, they can only sign power of attorney if they have the capability of doing so. If your adult child is not capable of signing a power of attorney, as their parent you can go to court to become your adult child's legal guardian. In order to consent to medical procedures for your adult child you must obtain power of attorney.