Every Adult. Under Wisconsin law, no one can make medical decisions for you unless you are a minor or you are married without a Health Care Power of Attorney. A Health Care Power of Attorney lists usually 2 people that you want to be your health care agent in the event you are incapacitated (meaning 2 doctors agree that you cannot make your own health care decisions). In a perfect world, the Department of Transportation would hand 18 year olds a Health Care Power of Attorney form when they turn 18 and come to the DMV to get rid of their probationary license. Assuming someone who is an adult is incapacitated and that adult does not have a Power of Attorney, a guardianship action must be filed to appoint someone to be their guardian. Guardianship costs a lot more than the free Health Care Power of Attorney form available on the Wisconsin Department of Human Service's website.
If you are married, but don't trust your spouse (that you maybe divorcing, separated from, etc.) to make your medical decisions, it is also time to fill out a Health Care Power of Attorney. Remember to follow instructions when filling out this form, ideally also execute a Living Will (available on the Wisconsin Department of Human Service's website), and sign this document before two witnesses that are not related to you. Many attorneys include these documents for free as part of an estate plan, and hospitals may also provide them to you in preparation for surgery.
As usually, this blog posting is not a substitute for legal advice from an attorney who knows your circumstances. No attorney-client relationship is formed by reading this posting.