Reporting by the Chicago Sun-Times provides new details about the monitoring of protest groups by city police.
The newspaper has uncovered seven Chicago police investigations involving the monitoring of protesters since 2009.
Information from city emails released after the Laquan McDonald shooting video went public show police and City Hall officials kept tabs on protesters.
Among the more recent examples, a top police department lawyer approved plans in October to have undercover officers monitor meetings of Black Lives Matter organizers, churches and philanthropic groups, according to the Sun-Times.
A police department spokesman described the probe as "routine" and within the law, adding that it was "documented to ensure transparency with the public."
"These protective actions -- which happen in limited circumstances -- are conducted to protect public safety and people's First Amendment rights," police spokesman Anthony Guglielmi told the newspaper.
The ACLU of Illinois is calling for Chicago City Council hearings into the police monitoring of protesters, saying the media reports about the "level and breadth of police monitoring of peaceful protest groups is unsettling and requires a response."