Philadelphia resident Charlotte McCoubrey vividly remembers when she got her driver's license at 16.

The Philadelphia resident, now 21, said her then-teenage friends would pile into the passenger seats, filling the car to full capacity for a trip to the mall.

"When you first get your license, it's great because you can drive around on your own and it seems easy," said McCoubrey, who was shopping at Suburban Square in Ardmore. "But you hear about car accidents involving younger drivers, which sometimes show how easy it is to get distracted and lose control."

As a result of these crashes, McCoubrey said she supports a law that went into effect Tuesday that places a new set of requirements and restrictions on young drivers.

Under the law, new junior drivers are permitted to have only one passenger under the age of 18 who is not an immediate family member without a parent or legal guardian in the car.

After six months, junior drivers who have not had a driving violation or accident can have three passengers under 18 in a car.

The new law also increases the amount of behind-the-wheel training time for young drivers from 50 hours to 65 hours. The added time includes 10 hours of nighttime driving and five hours of driving during bad weather.

The new law also makes failure to wear a seat belt a primary offense, allowing police to stop drivers under 18 if they or their passengers are not wearing seat belts or other proper restraints.

Drivers who fail to comply with the new law could get slapped with fines ranging from $10 to $75.

Frank Cantor, owner of Cantor's Driving School in Plymouth Meeting, said he thought the law was an excellent idea, but not strict enough. Cantor said he wanted Pennsylvania to also require junior drivers to wait a year after receiving their permit to be eligible for their license.

"Me personally, my daughter is seven weeks old and when it comes time for her to drive and the rules haven't changed, I might make her put in 1,000 hours [before her license exam]," he said.

Cantor, however, was pleased with the passenger restrictions for junior drivers.

"Junior drivers are more likely to get in an accident with more than one teenager because there's a lot of distraction, and the driver's getting asked to change the radio and do other things while dealing with a bunch of traffic," Cantor added.

Proponents of the law cited a recent state study that found fatal crashes involving 16- or 17-year-old drivers increasing from 40 in 2009 to 57 in 2010.

"I work with youth, and I know how easily distracted their brains can get," said Gail Graves, an occupational therapist in Lower Merion. "It's hard enough to drive as it is, so this law should help."

Julie Touchstone, a 20-year-old friend of Philadelphia resident McCoubrey, said she thought the law, despite its drawbacks for her younger peers, was necessary to prevent future fatalities.

"Yes, it might make life difficult if you carpool with friends for school, but if [younger drivers] are concerned about driving for fun, then they should realize it's better to remove any possible distraction," Touchstone said.

Patricia Lucas, 31, a new Wynnewood resident who came from Spain, was not aware of the law until Tuesday but thought it should also apply to adults.

"I know a lot of teenagers who drive well, and just as many older drivers who drive worse," she said.

Contact staff writer Josh Fernandez at jfernandez@phillynews.com.