If you don’t appoint a guardian and leave an advance care directive there is no guarantee that a person appointed to act as your guardian will be either the person you want or that they will make the decisions you would have made if you made them for yourself.
If you have not appointed a legal guardian, your medical treatment and health care decisions may be made for you by someone appointed by the government department responsible for administering guardianship issues. As mentioned, the person appointed may not even be someone that you may have appointed had you taken the opportunity to make the appointment yourself. This is clearly not desirable and to avoid it happening, all you need to do is complete a relatively simple guardianship appointment form and have it signed and the relevant certificates given as required under the Guardianship Act 1989.
However, the guardianship appointment form only ensures that the person you want has the legal capacity to make lifestyle and welfare decisions for you. Unless you also leave an advance care directive, then once you lose your capacity but subject to the Guardianship Act, the person you have appointed as your guardian will make all of your life style and welfare decisions in the way that they consider is right for you. If you leave an advance care directive, subject to complying with the law in doing it, your guardian is required to follow your directions.
If you don’t appoint a guardian and don’t leave an advance care directive, medical treatment and health care decisions for you may be made by someone you would not want making those decisions and they may make decisions that you would not make.
If you do appoint a guardian but don’t leave an advance care directive, lifestyle and welfare decisions for you may not match what you would have wanted done had you taken the opportunity to prepare an advance care directive.