As a small Jesuit school, Santa Clara is pretty strict when it comes to drinking and drug use, both on and off campus. Campus Safety officers patrol the dorms and campus pretty consistently and have little hestitation about writing students up for drinking or drug violations.
CFs, (Community Facilitators, just another word for RA) also patrol the dorms pretty regularly , although it depends on which dorm you're in. CFs in the larger "party" dorms, Swig and Dunne, tend to police more than those in the smaller dorms, but no matter where you are, if you're really loud and obviously drinking, you'll likely get written up. If you're written up for drinking or posession of drugs, the school fines you between $50 and $100, and requires you to do a few hours of community service and take an alcohol safety class. If you're caught by the police, the fine can be higher and they notify the University, who tack on their own fine.