A good friend just found out something like this happened to him recently.

He was in a really bad car accident (not his fault, drunk driver) and fractured his skull. Some minor brain damage, severe concussion. Was in and out of the hospital for over a year for his treatments.

He was done with the hospital visits, but still on the meds when he moved to a neighbouring city and decided to get a new family doctor closer to his new house.

After a few days the new doctor calls him with some questions. Why are you taking meds for a severe lung infenction? Medication for radiation sickness? This? This? My buddy had no idea and just said he's been taking the meds he was told to take for his accident.

Doctor calls back a day later, absolutely livid.

He found a contract/waiver/permission form of whatever saying that my buddy consents to participate in medical research testing the effects of taking various medications that he doesn't need. The signature is basically just a single pen mark. Comparing the date next to the signature and his medical charts from his hospital stay, this was while he was still severely concussed. Not only that, the charts clearly show that he was on so much morphine that he legally could not make any sort of decision like that.

The doctor recommended a lawyer, promised to provide his expert testimony, and now it looks like my buddy won't have to work another day in his life.