Actually, this may be an even bigger move than it first appeared. Jennifer Martinez-Roth, a mayoral spokesperson, tells me that possession of 15 grams or less would be a municipal violation subject to fines rather than a criminal offense. Police would still have the ability to make a full arrest if they deemed it appropriate, but it leaves open the possibility of cutting arrests and reducing criminal records of thousands of people a year. In short, it is a decriminalization proposal. And with Mayor Emanuel's support, it's almost certain to become reality.

Even Rahm Emanuel is conceding that something’s wrong with current pot laws.

The mayor is about to announce his support for a plan that would slightly lessen the consequences of getting caught with small amounts of marijuana, according to the alderman sponsoring the measure.

Danny Solis, alderman of the 25th Ward, says Emanuel has now given his backing to the idea of allowing police to ticket pot possessors. City Hall sources confirm that he'll make the announcement as soon as tomorrow.

The idea, says Solis, is to free up officers for more serious matters. "With what's happening in Chicago in terms of the violence, this is just a no-brainer."

Under the plan, people caught with 15 grams of marijuana or less would be given some sort of citation on site rather than cuffed and hauled to the station for booking, which typically takes two police officers off the street for at least an hour and a half.

But pot possession would remain a criminal offense in Chicago and cops would still have the option of locking people up for it. In fact, some reform advocates are concerned that the proposal is merely a way to let the mayor claim he’s doing something without making more substantive changes. They warn that the new approach is unlikely to narrow the grass gap—the disproportionate way that marijuana laws are enforced. African-Americans currently account for 78 percent of those arrested, 89 percent of those convicted, and 92 percent of those jailed for low-level possession.

Still, to most advocates it's a step in the right direction. Solis argues that it could make a big difference in high-crime communities.

"It takes up thousands of police hours a year that could be spent on the street," he says.

During the first five months of the year, Chicago police made 8,960 arrests for low-level marijuana possession, tying up more than 175 officer hours a day. These busts have cost taxpayers more than $22 million.

Solis first made his proposal last fall after calls for reforms from other public officials, including Cook County board president Toni Preckwinkle and county commissioner John Fritchey, who said current policies are unfair and costly.

Yet the mayor has been silent on the issue for months as the NATO summit consumed the time and attention of city officials. Earlier Thursday I reported that he still wasn’t talking, even as top officials in New York, including Governor Andrew Cuomo and Mayor Michael Bloomberg, announced plans to make possession a civil infraction rather than a criminal offense.

A few hours later, I started hearing whispers that things were moving again.

As expected, Emanuel isn't ready to join Cuomo and Bloomberg in supporting full decriminalization. But he's decided he has to do something.