In general, UWPD is fairly reasonable in their law enforcement. At parties, if students keep things under control and don't cause a lot of trouble, the campus police are most likely to leave the party alone. Usually, they only show up if a party disturbs neighbors in any way, if violence occurs, or if the party seems to be snowballing out of control in some other way. UWPD's main priority is to maintain peace around the University District, so safe and smart partiers will be left alone. UWPD tend to frequent the Greek area on prime nights, so be more careful at frat parties and on frat row. Don't walk from one frat party to another with a cup of beer in your hand, don't disturb others or be too loud, and if it seems like a party is getting sketchy, simply leave and go to another one. Also, if the cops show up, find a room and close the door-they can't enter without your permission.
The UWPD is much more strict with parking and driving enforcement than liquor or drug law enforcement. If you leave your car in a campus lot without a permit, it's likely to get ticketed within the first 15 minutes. Many students learn this the hard way. It's also a good idea not to let the speedometer creep above 25 mph-the speed limit on campus is 20-because they are fairly strict about enforcing the limit. In general, again, the UWPD are fairly reasonable. They're not out to get you, and in fact, they'd probably prefer not to have to deal with you. Their main priority is making sure you stay safe and within some reasonable boundaries of the law. If you don't bother them or anybody else, they won't bother you.