Saturday. Midnight. A cannonade of thunder from Point of the Mountain. The “party car” is 1 of 13 police cars patrolling the city. Charlie three-nine-nine, the party car, is manned by officers Mitchell Brooks and Jordan Robison. They will respond only to noise complaints until 4 a.m. Addresses, reported by fed-up neighbors, appear on a dashboard computer. One after another, the complaints queue on the glowing screen. Brooks plots efficient routes so they don’t waste time driving from one side of the city to the other. Robison drives the car purposefully. There is a sense of urgency as he negotiates the stops and starts imposed by traffic lights.

In a neighborhood of single-family houses, Robison and Brooks leave the car a half-block away. Walking on the sidewalk, they hear the birthday party before they see it. Music pulses into the dark street from a backyard lit by tiki torches. As they knock on the front door, “Copacabana” cranks up on a karaoke machine. “Her name was Lola ...” An off-key male voice assaults the Barry Manilow song. On the front porch, the conversation is friendly. The owner of the house concedes the music is too loud. And the singer is bad, he says as an afterthought. Robison and Brooks readily agree: “He’s bad!”

Back in the car, heading for a downtown hotel on the way to the university, the headlights illuminate a pedestrian in dark clothes crossing the street. Robison hails him with the rooftop loudspeaker as they pass: “Jaywalking is still a crime!”

Two blocks from Rice-Eccles Stadium, a standing-room-only house party is under way. Crowd noise drowns out any music that might be playing. Trampling Keystone beer cans underfoot, a scrum of college-age boys and girls dominates the front porch and yard. The party hostess tearfully explains that she doesn’t know most of the people and she can’t get them to leave, so, like sheep dogs, Robison and Brooks begin to work the edge of the crowd. Slowly, droves of partiers flow onto the sidewalk and head toward the university. Two girls linger. One laments the disappearance of her boyfriend in the party crowd. The other, a blonde wearing boots and a candy-cane-striped dress, launches into a matter-of-fact monologue. “I have to pee. I have to fucking pee,” she says to one of the officers. “I have to fucking pee, and I don’t want to do it in the fucking street.” The police are paternalistic. They get her back into the house to urinate. “You guys are cool,” says the abandoned girl. “I lived in Pennsylvania where the cops were nasty.” The policemen return to the car, turn on the red and blue lights and drive slowly around the block. “Move along,” Robison tells loiterers through the open window.

Then they are off to a housewarming party near the Brickyard Plaza. A burly man in a sleeveless T-shirt answers the door. In the ensuing conversation, Brooks explains that the party car doesn’t crash parties; it responds only when neighbors call about the noise. “What?! They don’t like ’80s music?” the man says, laughing. Brooks, though a baby in 1986, says he is a fan of The Cure and Depeche Mode.

At 1 a.m., rain falling lightly in the Yalecrest section of the city, a brick bungalow seethes with college students. Robison and Brooks walk into the xeriscaped yard. “The cops are here!” someone shouts. No one runs. The policemen talk with the host on the porch, and the party begins to break up in slow motion. More than 100 boys and girls drift out of the house and yard and disappear into the night.

One of the last to leave is, again, the blonde in the candy-cane dress. Swaying slightly, she wants to talk some more. “I don’t drink,” she says to the officer. “I don’t drink because of my religious upbringing.” He tells her she should go home. He asks where she lives, and she points to a nearby house. “I don’t want to go home because nobody is there,” she says and wanders off. A boy cradling a skateboard watches idly. “The police are anti-fun,” he grumbles.

In a time of shrinking budgets, the police are forced to prioritize. Deploying the party car for five hours a night enables them to respond to dozens of disturbing-the-peace complaints without compromising their ability to deal with serious problems. It is safe to say, I think, that most residents of Salt Lake City have never been disturbed by a raucous party. Given that, it is conceivable that many would deem the party car an extravagance, one as unnecessary as the beer and fireworks patrols outside of Evanston. However, to continue to fund enforcement of noise ordinances is in line with criminology’s “broken windows theory.”

According to the theory, turning a blind eye to noise, graffiti and other misdemeanors is conducive to escalating crime. A vacant building with one broken window soon has all of its windows broken. Then someone breaks in to party, to sleep, to rip out copper pipe or to start a fire.

Fixing the first broken window nips escalation in the bud. So, if you are making noise and neighbors complain, expect the party car to pay you a visit—albeit a friendly one. A second visit costs $300. If you are a party-on dude living in an apartment and the police come knocking repeatedly in the course of a year, the landlord is going to pay some fines, too. However, Robison says one visit is usually enough. Most people are compliant because they know they are making too much noise. “It is pretty rare to come back.”