CHICAGO (CBS) – The city’s most influential alderman on Monday said he had serious concerns about Mayor Rahm Emanuel’s plan to decriminalize possession of small amounts of marijuana.

Ald. Edward Burke (14th), who chairs the City Council Finance Committee and is the council’s longest-serving alderman, said he’s not necessarily opposed to the mayor’s plan, but he wants more details about when police would be able to issue tickets instead of making an arrest.

“I’m not saying we shouldn’t do this. I’m saying there’s a lot of questions that ought to be answered,” Burke said.

The mayor’s proposal would give officers the option of giving offenders a ticket with a fine of up to $500 for those caught with 15 grams of marijuana or less.

Burke said the Police Department needs some clear rules on when officers would be allowed to make an arrest in such cases, rather than simply issuing a ticket.

“I think that has to be made very clear, and the Police Department has to show us – I think – that they’re not just going to blindly issue tickets to everybody that’s in possession of small amounts,” Burke said. “There has to be a certain strategy to know which of these people that they could write a ticket to are eligible for a ticket.”

He also said he’s worried about the message that decriminalizing small-time marijuana cases would send to the city’s youth.

“Is this a slippery slope that we begin sliding down? I’ll tell you, as a parent, I’m very concerned about anything that gives kids the idea that this is not a bad thing to do.”

Burke also said the mayor’s proposal could create a big problem in cases when a person caught with a small amount of marijuana is not carrying identification, which could allow them to essentially get off scot-free by lying to police about who they are.

“I’m sure that most cops will tell you that writing a ticket might make some sense, however to write a ticket for somebody who has no identification is a serious administrative problem. How do you write a ticket to somebody that doesn’t have a driver’s license or identification?” he said. “Do you believe what the person says? ‘My name is Joe Blow,’ or, ‘My name is George Washington,’ and he’s got no identification to back that up? How do you then guarantee that person is ever gonna show up for the administrative hearing?”

Under current law, possession of any amount of marijuana includes arrest on a misdemeanor charge, and penalties of up to six months in jail and a $1,500 fine.

The ordinance to lessen the penalties was introduced last fall by Ald. Danny Solis (25th). Supporters say it would cut the cost of jailing those caught with small amounts of the drug, and encourage police to focus on more serious crimes.

Last year, 18,298 arrests were made for possession of less than 10 grams of pot, but the vast majority of misdemeanor marijuana cases are dismissed, according to the mayor’s office. Each case requires the manpower of about four police officers – two for an arrest and two for a transport – and places a burden on the Cook County court and jail system.

The Police Department has said minor marijuana cases tied up more than 45,000 police hours last year, and the mayor’s proposal could cut that time in half.

–CBS 2 Political Producer Ed Marshall contributed to this report.