Describing herself as “damn angry,” Mayor Lori Lightfoot lashed out at the Chicago Police Department on Wednesday for using its vast resources to conduct criminal background checks on average citizens who signed up to speak at Police Board meetings.

One day after the Chicago Tribune disclosed an alarming practice that harkened back to the Chicago Police Department’s Red Squad spying days, Lightfoot called a halt to it and condemned the practice in the strongest of terms.

“I can’t say I’m stunned, but I’m really damn angry about it. This is never gonna happen again … When I found out about it, I … immediately directed that the practice stop. It’s just stupid,” Lightfoot said.

“People should be able to come to a public gathering, stand up, sign their name, state whatever they want without the fear of being investigated by the Chicago Police Department. They know they have to own this. I’ve been very clear with them that they have to own this. It was foolish. It started back under former Superintendent [Garry] McCarthy and just got carried forward thoughtlessly.”

Lightfoot was twice appointed Police Board president by now-former Mayor Rahm Emanuel. That’s the platform she used to hammer Emanuel, declare her candidacy against him and, when he chose political retirement over the uphill battle for a third term, win the office that Emanuel vacated.

Clearly, she had no idea that the meetings over which she presided had triggered background checks on public speakers.

“We looked to make sure that it wasn’t being done in any other places where there are public comment periods,” she said.

The mayor was asked whether she has gotten an explanation from Police Supt. Eddie Johnson about why the background checks on public speakers were conducted in the first place.

“It started back in 2013 as best we can tell, and it just kept going forward. My sense is nobody even made any use of the information. It was just, `OK. Police Board meeting. We now have the list. Let’s run the checks,’ ” the mayor said.

“It’s that kind of thoughtlessness that is a problem. We have to have our Police Department …engage in constitutional practices. That’s a lot about what’s gonna happen over the course of the consent decree. But I want people to exercise common sense. This was just stupid.”

The Red Squad was a controversial and now-disbanded intelligence unit within the Chicago Police Department that specialized in infiltrating political, labor and social groups to gather information on them.

Lightfoot unleashed her anger after an action-packed City Council meeting that was the last before the traditional August recess. In other action:

— Ald. Matt O’Shea (19th) proposed that the City Council exercise its right under state law to impose a 3 percent “excise tax” on the sale of recreational marijuana in Chicago. Under O’Shea’s ordinance, proceeds from the local tax would be used to solve the city’s pension crisis.

— A companion ordinance would prohibit the sale of marijuana within 500 feet of a school, park or other facility that primarily serves children. O’Shea also introduced a third ordinance that would increase the real estate transfer tax on homes sold for more than $1 million and use that money as well to shore up the four city employee pension funds.

Lightfoot wants to raise the real estate transfer tax to eliminate the city’s budget shortfall. Other aldermen want to use it to reduce homelessness, create more affordable housing and replace lead service pipes they fear are contaminating Chicago’s drinking water.

— At the behest of downtown Ald. Brendan Reilly (42nd), the council approved another “zero tolerance” crackdown on daredevil motorists who use Lower Wacker Drive and other local streets as a track for their “Fast & Furious”-style drag racing and spin contests.

— Ald. Ray Lopez (15th), who has emerged as Lightfoot’s most outspoken City Council critic, introduced legislation that would defy the mayor’s executive order and require applicants for all city land sales, land-use agreements and land swaps within the greater Englewood community to first get a letter of support from the local alderman. Lopez said there are 2,462 city-owned properties in the six wards that include Englewood, and local aldermen know best about what to do with those parcels.

— Lopez, the City Council’s resident dog-lover, proposed that the city license private shelters and prohibit “pet leasing.” The shelter ordinance is aimed at preventing a repeat of the tragic fire that killed 31 dogs at a private trainer’s shelter in West Chicago.