Determined to prevent party buses from turning into what one aldermen called “rolling cemeteries,” the City Council on Wednesday went about as far as it legally can to rein in the rowdyism and violence.

“Party buses are supposed to be for celebrations — not potential rolling cemeteries where armed, sometimes fatal violence can break out at a moment’s notice thanks to the potent mix of guns and alcohol,” License Committee Chairman Emma Mitts (37th) said minutes before her committee advanced the crackdown to the City Council floor for the final vote.

Mitts urged her colleagues to act quickly “for every parent whose young person wants to experience party buses for a birthday, prom or graduation.”

Emanuel had promised to “push the envelope” to prevent passengers from carrying concealed weapons aboard party buses after 10 shootings and one homicide over the last two years and after three semi-automatic weapons were discovered on an overcrowded party bus last weekend.

But aldermen were told Wednesday the mayor was forced to settle for something short of an outright ban because only the Illinois General Assembly can amend the state’s concealed-carry law by adding party buses to the no-guns category that now includes restaurants and bars.

Instead, party buses with 15 or more passengers that have alcohol on board or make interim stops where alcohol will be consumed now are required to hire “licensed security guards” instead of “chaperones.” They would also be required to install video cameras.

The bus owner, driver or security guard are required to take “affirmative measures to determine that no passenger is illegally carrying a firearm.”

Business and Consumer Protection Commissioner Samantha Fields did not explain what those “affirmative measures” can be.

But Deputy Corporation Counsel Jeff Levine acknowledged that any “affirmative measures” would be on shaky legal ground so long as the state’s concealed-carry law still allows patrons to carry concealed weapons on party buses.

“The state law creates a right to concealed carry and sets out specific exceptions, which includes bars, government buildings. Buses are not included,” Levine said.

“So a bus company could include that as a condition. But, they might well be subject to an argument that a person is being constrained in violation of state law.”

Ald. Michael Scott (24th) countered that most party buses are “rolling bars” that serve alcohol. He argued that city attorneys should make that argument and try to push the envelope even further.

“I am supportive of the measure. I just think that it also should go a little bit further so we have even more protections in place,” Scott said.

“It is a deadly mix to have alcohol and firearms in one given place. And that’s why they prohibited them in bars. I would think that we would try to enact the same argument for a party bus because of the mixture of alcohol and firearms.”

Levine said that’s an argument that could be used to justify a change in state law.

Downtown Ald. Brendan Reilly (42nd) was the first to introduce what has been a series of crackdowns that have failed to rein in the rowdyism and violence.

On Wednesday, Reilly decried the “increasing trend of bad behavior” on party buses that can only be solved in Springfield.

“I know that the mayor and others are frustrated that we don’t have the ability to restrict firearms on these party buses. But all of us can speak with our local legislators … to ask them to make this a legislative priority,” Reilly said.

“Ald. Scott raises a very good point. … These are effectively rolling bars. If the state saw fit to restrict that kind of activity in bars, they would think this is a reasonable extension of that restriction.”

Reilly noted that party buses are not unique to Chicago. It’s becoming a “suburban problem as well,” he said, so partisanship doesn’t matter. “It’s just a matter of time before suburban legislators will be asked to help handle this issue as well.”

Ald. David Moore (17th) cast the only vote against the ordinance, primarily because of the prominent role it requires security guards to play.

“Although we have some great police officers who know how to de-escalate and are learning even better now how to de-escalate situations, I don’t want any trigger-happy security guard. Then, he shoots someone and I’m in defense of my life,” Moore said.

Moore said there is also “an element of privacy” to party buses.

“To have someone sitting back there in your group that you really don’t want in your group — sometimes it can stir up situations. … You’re talking about adding another element in here that may cause some problems. … If something goes down — something as silly as checking out these women on a party bus — the whole party could end up beating the security guard’s butt.”