I am my sons medical power of attorney. A doctor amputated half of both of his feet without my consent. Is this legal?

Your inquiry raises many issues for which additional information would be needed to give you a more specific answer. From what I can gean, your son appears to have significant medical issues based upon your "all other surgeries" comment.  The issue is whether -- had you been asked -- you would have consented to the surgery.  If the amputations were medically necessary and if you would have consented, then there is likely very little recourse for you.  For example, severe diabetes can lead to all types of extremity amputations that cannot be delayed or avoided. Frankly, you need to sit down with a medical malpractice attorney who can obtain a full history as to your son's medical situation to help you determine whether you have a viable case and whether your case is financially worth pursuing. There are situations where malpractice has occurred, but the cost to pursue the claim exceeds the likely recovery.