Why law enforcement from Milwaukee's suburbs and beyond are able to assist Milwaukee police during protests

Over a long few days of protests, a number of police departments and law enforcement agencies from across the area have been seen in Milwaukee. 

Vehicles and officers from the Racine County Sheriff's Department, Brown Deer Police Department, Glendale Police Department, Waukesha Police Department, Kenosha County Sheriff's Department and more have been seen within Milwaukee city boundaries. 

They're able to assist Milwaukee police in dealing with the protest under "mutual aid," which essentially allows another municipality's department to assist a department that asks for help. 

The Milwaukee Police Department's standard operating procedure says requests for mutual aid must be made by the police chief or his designee. 

On Sunday night, a City of Waukesha rescue vehicle was on the east side of Milwaukee. Waukesha Police Capt. Dan Baumann confirmed there was a request for the vehicle to come to Milwaukee. 

"We have formal lines of communication when it comes to mutual aid agreements. Some are long-term written intergovernmental agreements, some are dynamic as an incident evolves rapidly," Baumann said. 

Baumann said Waukesha could also request help from Milwaukee. 

Departments across the state use mutual aid, as in the case of the high-profile Jayme Closs case, where the teen was abducted by a man who kept her locked in a house for 88 days after killing her parents in northwestern Wisconsin in 2018. Several law enforcement agencies assisted in the search, through a mutual aid agreement between departments. 

For this story, several area police departments did not respond to questions about what current written mutual aid agreements are in place in their jurisdictions. 

Mutual aid agreements are discussed in Wisconsin state statute 66.0313.

Such agreements are not unique to Wisconsin, but are used by police nationwide.

On Monday, Libby Garvey, a board member in Arlington County, one of Washington D.C.'s neighboring suburbs, tweeted about withdrawing mutual aid police after law enforcement officers cleared a nearby park in Washington, D.C., so President Donald Trump could walk to a church. 

Aside from mutual aid agreements, law enforcement agencies in Milwaukee County can make arrests anywhere within the county, under a Wisconsin law. 

"For any county having a population of 750,000 or more, if any law enforcement officer has territorial jurisdiction that is wholly or partially within that county and has authority to arrest a person within the officer's territorial jurisdiction, the officer may arrest that person anywhere in the county," a state statute says. 

Evan Casey can be reached at 414-403-4391 or evan.casey@jrn.com. Follow him on Twitter @ecaseymedia.