A Girl Scout troop in Colorado studied the effects of smoking and wanted to do something about secondhand smoke.

So the teens approached their troop leader and told her they wanted to write a law and propose it to the Aurora City Council to limit smoking, specifically banning lighting up in cars when kids are present.

"It was out of the blue," said troop leader Kristen Batcho, who works in finance and does not have any political or legislative experience. "I said, 'We've never done this before.' "

But she quickly decided: Why not?

And thus begins the story of how the Aurora City Council outlawed adults smoking in cars with minors. The law took effect last week, with violators facing mandatory community service.

"I'm not a sentimental guy, but it gave me a real renewed faith in the youth of our country," said Aurora City Council member Charles Richardson, who met with the five-girl troop every few weeks for about a year and helped them write the law. The girls, who are 13 and 14, got some help from the council member's legal team, too.

The vote was a nail-biter, with Mayor Steve Hogan casting the deciding vote in favor of the bill, which passed 6-5 last month.

"When the mayor cast his vote, my daughter started crying," Batcho said. "There was this sense of relief. Their hearts could stop pounding out of their chests."

The bill was controversial in the city of 360,000 people. Some thought it was too much government reach, that smoking in cars should not be policed. Others thought it targeted minorities and the poor, as people in those communities tend to smoke more than other populations.

But in the end, the Girl Scouts prevailed.

Richardson said he has a personal connection to the idea behind the bill, as his wife has asthma and grew up with people who smoked while she was in the car. "I believed in it from outset," Richardson said.

He said that when he was first contacted to meet with Troop 60789 about a-year-and-a-half ago, they asked if he could come talk about how city government operates.

"I met with them, and they informed me they wanted to move forward on a piece of city legislation," he said. "I was, frankly, thinking it would be a resolution adopting a city insect or bird or flower. This was something much bigger."

In the process of developing the bill, the girls did research on secondhand smoke and presented it to the council. They also learned about how politics works.

The bill was amended from its original form, in which violators would face a $150 fine. As it was originally written, police could have stopped someone if they suspected they were smoking with a child in the car. But when the measure passed, that was changed so police can only write up violators if the officer has already stopped them for another reason such as speeding or running a stop sign.

"They learned good political lessons about give and take," Batcho said "Sometimes you have to tweak things to get your idea passed. It was a lesson in civics."

The law will have a six-month phase-in period, when police will give warnings rather than write tickets.

Batcho, who has been the troop leader for six years, said she's known some of the girls since they were in kindergarten and has watched them grow up. Knowing how determined they were prompted her to agree to the project, which earned them a "silver award," the second-highest honor in Girl Scouts.

She said she could not be more proud of her troop.

"It tells the girls that, yes, you do have a voice, and you can step up even if you're 13 and 14, and you can do great things," she said. "They might be small, but they are mighty."

Other troops in the community have asked Batcho's troop to speak at their meetings and explain how they did it. Batcho said her girls are excited to talk to the other troops. But it will have to wait a few weeks, because in addition to classes, a school musical and choir, the girls are now consumed with something else: Selling Girl Scout cookies.

"Let's get through cookie season first," she said.

Staff researcher Jennifer Jenkins contributed to this story.