"When you start having crime spikes, curfew allows you to stop people," Batts told the website OaklandNorth.net in 2011. "And if they have the fear that you're going to stop them, they're going to leave the guns at home."

The proposal met with resistance in Oakland; Batts said he was told the city was "too progressive for that." Batts resigned from his post in Oakland, citing a lack of support from city leaders, one week after a curfew and other initiatives failed in the City Council.

In March, the Baltimore Police Department used its Twitter account to float the idea of an earlier curfew. But Batts backed down days later, telling residents at a community meeting that he had "stirred the pot" and was told to "leave it alone."

"I think the concept needed to be vetted properly for potential issues," Batts said in an email Tuesday, when asked to clarify the remark.

Jason Tashea, juvenile justice policy director at Advocates for Children and Youth, said the nonprofit organization is still studying the curfew legislation. He's hopeful the proposal opens a dialogue that also prompts city leaders to consider investing more resources in after-school and recreational programs.

"While we think that it's wonderful the mayor, the council and police are looking for ways of solving juvenile delinquency as well as youth victimization and crime, we have a number of questions and concerns we haven't had answered yet."

Tashea said an analysis of juvenile arrest rates — excluding warrant arrests — shows the majority of crimes committed by teens happen during the day and after school. Only 12.2 percent of juvenile arrests were made between 11 p.m. and 7 a.m. so far this year, he said.

"My interest is to know what their motivator is, if they have particular information to say this is a good working program," Tashea said. "Looking at these numbers, I wonder what they know that I don't."

Baltimore Councilwoman Mary Pat Clarke said she supports a curfew for the "safety of the children and for the well-being of the community," but said enforcement must be weighed against the other priorities before police at any given time.

Clarke was one of the biggest proponents of the city's initial efforts to establish a curfew in the 1990s, saying then that the city was on "borrowed time" without a juvenile curfew.

"It is our way to protect children when families won't," Clarke said. "Our children are safer in the curfew center than they are in the middle of the street a block away from people with guns."

Kumar said officers would have wide discretion over how to enforce the law. She questioned how an officer would determine a child's age and whether they are on the streets for one of the exceptions allowed under the proposal.

"We've heard a lot from kids about their interactions with police, and the stories we've heard don't inspire confidence that this proposal will be implemented in a way its proponents believe it might," Kumar said.