Like every professional “driver” an airline pilot is legally required to be under the drink-fly limit ( 20mg of alcohol per 100ml of blood UK -US 40mg )before he embarks. Likewise, a pilot is under a legal and moral obligation to refuse to fly with another pilot whom they suspect of being over the limit.
Just so you understand a pilot has a licence to fly, not the company, so any pilot can refuse to fly if they think it is unsafe to do so and the company would be in a whole lot of trouble if they did not accept and rectify the problem (if it was possible).
To give an example I, on a couple of occasions, refused to fly because of unacceptable weather conditions on the North Sea and despite pressure from the company stuck to my decision. The company then accepted that I was not flying.
P.S. In the Army we had very strict limits. No drinking within fifty feet of the aircraft and No Smoking with eight hours of flying………………at least I think that was correct.