You drink. You work. You lose.
Ok, that sounds like a cheesy anti-DUI commercial, but it's true, at least when it comes to Illinois workers' compensation.
If you are drunk on the job and get in an accident because you were drunk (or high), you will not win a claim for workers' compensation benefits. Strangely enough, if you are just sitting at your desk drunk and something happens (e.g. a forklift crashes in to you) that has nothing to do with your drunk state of mind then you'd probably have a case.
Traveling employees are actually allowed to drink on business trips and still win benefits if they get hurt unless they are sloshed. In other words, if you are out of town for business and have a couple of glasses of wine at dinner, but then fall in the parking lot, you'd probably have a case if you didn't fall because of the drinking.
On the flip side, a few years ago we got called by a trucker whose rig broke down at a rest stop. He was stranded so he drank about 30 beers and fell out of his truck and blew out his knee. That case is not a winner because while it's foreseeable you might have a beer, it's not foreseeable that you'd drink that much and put yourself in harms way.