"This was no an accident - you were drinking - and your drinking caused your injury."
This happens with some frequency in car accidents, especially one car accidents.
Can they do this?
The general answer is "yes."
Most group health plans are governed by ERISA. This is the federal law regulating health plans and other employee benefits. Except the law really isn't so much about regulating plans as it is about giving employers the freedom to have anything at all in their policies. These policies are by and large unregulated, even by state insurance law.
So this allows a health plan to deny you coverage. Which means that guess what? The doctor and hospital doesn't get paid.
I wonder how long it will be before hospitals stop testing for alcohol use when the one car accident victim gets brought into the emergency department?