There isn't one answer when it comes to strictness at Williams because it varies with the nature and seriousness of a situation. Campus Security’s strictness depends on the officer, but almost all officers ignore parties involving beer and Beirut, and others will occasionally join in on the game. The head of security dislikes hard liquor and will sometimes write people up for it. So, the rule of thumb is drink beer in the common room (unless you’re a Frosh) and take shots in your room. It’s not the safest system, but it’s the easiest way to party without getting in trouble.
One must weigh the consequences of a late library book versus that of alcohol poisoning, and many feel Williams College security should, too. While Williams has many rules, most students do not find it difficult to follow them. Rules should be observed with equal rigor, both when it comes to library policies and underage drinking.