Infrequently, a driver afflicted with a medical condition will lose control of the car and cause a collision.
What is MORE common is the driver's insurance company claiming that the driver is not liable to pay the injured driver's damages in a personal injury claim/lawsuit because of a "sudden medical emergency."
For example, if a diabetic has a hypoglycemic (low blood sugar) episode and causes a crash, his insurance company may well deny being liable for the injuries he causes due to a "sudden medical emergency." Other classic examples of this accountability avoiding insurance tactic include drivers with epilepsy or heart ailments who become incapacitated due to those conditions while driving.
This is almost always a bogus defense, for a number of reasons. First, the definition of a "sudden medical emergency" under Ohio law is where the driver "is suddenly stricken by a period of unconsciousness
which he has no reason to anticipate and which renders it impossible for him to
control the car he is driving."
In other words, the "sudden medical emergency" must have been unforeseeable. Problem: most medical emergencies are quite foreseeable, even if not predictable as to exactly when they will occur.
Take the diabetic , for example. Most folks with this unfortunate condition must frequently manage their glucose levels. Because they can often fluctuate, even with careful management, their blood sugars can often rise or fall to dangerous levels, and cause impaired or lost consciousness or even seizure activity. Their insulin pump readings (which can store average glucose readings for months will often show dangerous fluctuations in glucose levels. What's more, their medical records (from their internist or endocrinologist) may have documented previous incidents of problems, such as emergency trips to the hospital to re-regulate their glucose levels, and other evidence of lapses of consciousness.
Very rarely is unconsciousness due to a diabetic event ever considered an "unforeseeable" or "unanticipated" event.
What would be a potentially good example of a truly unforeseeable sudden medical emergency? A driver with no history at all of any heart problems or history who has a heart attack at the wheel, passes out at the wheel, and injures another motorist. That's about as rare as a politician at a truth convention...
Absent something like that, drivers (and their insurance companies) are not excused from liability for injuries caused while under a medical condition. In my 25 years of personal injury practice, I have yet to see this defense work. Whenever it has been raised, it has usually died on the vine after a subpoena for the driver's physicians' medical records, which will often show the paper trail of problems that preceded the crash.