A major problem is that there is a tacit acceptance of drinking in many school systems. Then when the students go to college, the ones who used to hide their drinking from their parents are now living in an environment in which mom and dad aren't there to keep things in check. And the University cannot totally assume the parents' role. However, those who engage in alcohol-related misconduct on or off campus are subject to disciplinary action at Boston University, and that includes expulsion. Several BU students interviewed by the BU Bridge say that the University's alcohol policies are effective, but to paraphrase an old saying, if there is a will to drink, there is a way.
Students can get fake IDs and drink anyway.
But I think BU enforces its rules as much as can be expected. But BU is pretty aggressive when it comes to keeping it out of the residence halls where minors live.