The hot-button issue has quite a bit of history to it. How many officers are assigned to each of Chicago's police districts? What's the breakdown of high priority 9-1-1 calls? And do those districts with more violent crime have an equitable number of cops to deal with them?
The ACLU says the answer to the last question is no.
"Every police superintendent for the last 15 years -- with the exception of Cline -- said they were going to re-deploy officers," Harvey Grossman, ACLU, said.
But the ACLU's argument is that it doesn't happen, because ultimately it becomes politically unacceptable to move officers from lower crime to higher crime neighborhoods.
The police department has declined over the years to reveal how it staffs its districts, but the ACLU says through Freedom of Information requests and news analyses, it now has the numbers to make its case - and in its most basic form it is that neighborhoods with higher rates of violent crime still have fewer officers patrolling than neighborhoods with less serious crime.
"This disparity has been going on for many, many years. We want it addressed now. we think it requires judicial review to get a remedy," Grossman said.
The city isn't commenting on the specifics of the lawsuit, but the mayor Thursday underscored his campaign pledge to put more officers on the streets.
"So I understand they brought the lawsuit, but we're ahead of where we were May 15. We're not done with our review of resources. It's not just about manpower alone," Mayor Rahm Emanuel said.
Ron and Serethea Reid moved into the West Side Austin neighborhood four years ago, and say they and their neighbors routinely witness open air drug dealing and some violent crime. Their calls to 911, they say, bring responses that are tardy if there's a response at all. And the upshot they say is that people have just stopped calling 911.
"Their expectation is very low that anything is going to happen with they make a calls so there's a lot of calls to us, but people don't always make calls because they don't expect anything. The other reasons they don't make any calls is because they fear retaliation," Reid said.
The ACLU's lawsuit is filed in state court alleging a violation of the Illinois Civil Rights Act of 2003. That act is meant to prohibit governmental policy from having an inequitable impact on different racial groups.
The ACLU says it hopes the lawsuit sheds some light on the process.