When you invite your 100 best friends to a party on Facebook, you may be inviting the Madison Police as well.

The Madison Police Department has begun searching the popular social networking site Facebook to find out where parties are being held around the University of Wisconsin campus. Students who post public events with detailed information about their party can be contacted about it by the MPD.

Sergeant Dave McCaw of the MPD Central District Community Policing Team said the department has been using Facebook as a preemptive measure to warn students about the dangers of hosting illegal house parties before they actually occur.

“What we use Facebook for — and have for some time — is, if we find out that these parties are going to happen and they’re pre-advertised, we contact them as soon as we possibly can,” McCaw said. “We let them know that we know. We have several pamphlets that we give out. We discuss with them the ramifications should they have an illegal house party and actually give a price list of what everything could cost.”

After warning a residence that the department is aware of their intent to host a party, the police try to revisit the residence during the scheduled party time, McCaw said.

Illegal house parties are constituted as any party at which the hosts are selling alcohol and thus acting as a bar, McCaw said. He also said people can get tickets for possessing alcohol while being underage as well as furnishing alcohol to someone under 21.

UW junior Abbie Lynch was contacted by the MPD through her landlord and was told the police knew about her party scheduled to be held during the Mifflin Street Block Party on May 3. She went through with the party but made sure attendees brought their own alcohol.

Lynch had created a public Facebook event so she and her three roommates could invite people to their party on Mifflin Street. The Facebook event stated they would be selling T-shirts to attendees to pay for beer.

The MPD informed Lynch this was illegal and warned that dispensing alcohol to the 75 Facebook-confirmed attendees would count as acting like a bar.

“We didn’t really think it was a problem, but apparently it was,” Lynch said.

After her landlord told her the police were aware of the scheduled party, Lynch contacted the police.

“[An officer] told me had we continued doing what we were doing, we would have gotten a ticket, but if we had told our guests it was BYOB, we wouldn’t,” she said.

Lynch said she and her roommates changed the Facebook event to “bring your own booze” but left it public.

“We changed it right away because we figured if they were looking at it, we would keep it public and like let them know that we were making steps to change what we were doing,” she said.

The roommates survived Mifflin without getting any tickets but were disappointed they couldn’t provide for all of their friends, according to Lynch.

But not all preemptive police visits stop students from hosting parties. UW sophomore Dan Brundage said a party in his apartment was busted after no one was home when the police came to warn them.

“They knew we were selling [liquor] because we had put prices on the Facebook event, so they knew exactly what we were doing,” Brundage said.

Police told Brundage and his roommates when they arrived at the party last November that they had tried to warn them beforehand. The four roommates, all under 21, received about $700 worth of tickets each after they agreed to stop the party.

“It could have been a lot worse if we didn’t cooperate,” Brundage said. “If we would not have let them in and not cooperated, it would have ended up being $13,000 a person.”

Had they known the police were aware of their party, Brundage said they would have rescheduled the party. He and his roommates had their fines reduced in court but will be on probation for the next year. If any of them receive any more alcohol violations, they will have to pay the $300 that was knocked off on top of any new fines.

UW Police Lt. Eric Holen said his department doesn’t use Facebook in the same way because the department deals mainly with parties in university dormitories. According to Holen, the UWPD has used Facebook in investigations before, though he preferred to keep exact techniques secret.

“It is a tool that we know is out there in terms of information, but I’ll tell you we just don’t have the time,” Holen said. “We don’t have someone whose job it is to be perusing Facebook looking for parties. The parties on campus we have no trouble finding as it is, because usually there’s associated behaviors with them” like noise or fighting.

Ald. Mike Verveer, District 4, said he doesn’t think the police should be spending their time finding parties online.

“It’s hard to justify, at least for me as a representative of dozens of students downtown, how the police can make the case that they have the luxury to find the time to search on Facebook for house party public event listings,” Verveer said.

He said with growing safety concerns in the downtown area, the police should not be focusing on catching underage drinkers.

“I can’t tell the police not to use Facebook, but I just think it’s a silly use of police resources when there’s so much going on today with crime in the campus area,” Verveer said. “A lot of students are on edge, and rightfully so, in the last month.”

McCaw said it is rare for the department to have time to search Facebook for parties.

“We just don’t have time to do it,” he said. “For about a year-and-a-half now the downtown safety initiative has been the issue. And quite frankly we just don’t see the house parties like we used to be (seeing them).”

Still, McCaw said students shouldn’t feel threatened by the pre-emptive measures used by police, comparing them to a sign notifying speeders of an upcoming radar trap.

“I don’t take that as a threat at all,” he said. “I take it as if you don’t want the ticket and these are the criteria for what will happen, then don’t do it.”