Strange how habitual marijuana users always defend their habit by saying “well, look at THAT, it’s legal and it’s not as bad!” Even if true, it’s not a very logical defense. It doesn’t actually say anything at all about marijuana, and you always run the risk of losing the argument to some teetotaler jumping up with “well, then THAT should be illegal too.”
If someday you become an H.R. director, then you can make your judgment about the relation of alcohol abuse to job performance and institute policies the way you see fit. Maybe it is more detrimental to work than marijuana, maybe the employer’s making a bad decision with his policy, but he’s still free to make that bad decision.
The other thing to consider, though, is the effects of alchohol are varied. One can drink a couple beers watching the football game Monday night and not get drunk or in any way intoxicated. You can drink for reasons like taste that have nothing to do with getting intoxicated and you can moderate it so that you are ok after use. It’s certainly possible to smoke say…ONE drag off a joint…and not get high. But who the hell smokes pot for any reason other than to get high? It sure ain’t the taste. You smoke, you get high, and you’ll be that way for a while no matter what you do. OTOH, it’s possible to drink every day and never get drunk. If you smoke pot even occasionally you will be high at some point. So evidence of alcohol usage doesn’t really tell you anything about that person unless you know his particular style of drinking: casual, or binge? You don’t know if that person is ever drunk. Evidence of potsmoking tells you that person does become high. To an employer, this might be enough to make the judgment call that the potsmoker is potentially unreliable, and he’ll hold out on the alcohol user until he knows more. It’s his call.