Some 25 years of experience separate Terry Kernan's opinion of Maryland's new restrictions on novice teenage drivers from that of Melissa Justice.

The rules, which take effect today and which were approved by legislators this year after a rash of fatal crashes in the state, include prohibitions on underage passengers, restrictions on cell-phone use, a longer apprentice period and more night-driving practice before teenagers get their licenses.

To Justice, a 17-year-old who took her driving test this week at the Maryland Motor Vehicle Administration in Waldorf, the limits on carrying passengers are an inconvenience.

"What if you break down on the side of the road and you don't have your cell phone?" asked Melissa, a junior at Huntingtown High School in Calvert County.

But Kernan, 43, father of a 15-year-old boy, supports the new rules. Waiting in the Gaithersburg office of the MVA while his son took his driver's test, Kernan recalled his own initiation behind the wheel.

Three days after getting his license, Kernan, then a high school junior, left a football party with friends packed into his mother's Dodge. In a tight driveway, he encountered a vehicle coming the other way and he started to back up. He tried to step on the brake pedal but actually hit the gas.

"I had to go home and tell my mom that I wrecked the family car. Our only car," Kernan said.

Kernan feels strongly about the changes. "If anybody complains [about the new laws], shame on them. They're putting their convenience in front of the kids' safety," he said. "If I would have had those restrictions, I wouldn't have wrecked my mom's car."

Maryland joins a growing number of states with such laws on the books. The District and 31 states, including Virginia, have limits on teenage passengers, said Keith Holloway, spokesman for the National Transportation Safety Board. Eleven states and the District have restrictions on cell-phone use for teenage drivers; the Virginia House rejected such a bill this year.

Descriptions of Maryland's six new teenage driving laws have been sent to high school principals, parents of novice drivers, state legislators, and law enforcement officers. The Maryland MVA outlines the changes on its Web site.

Under one law, teenagers with provisional licenses would be prohibited from carrying teenage passengers who are not family members during the first 151 days of the 18-month provisional period.

Under another law, anyone younger than 18 who has a learner's permit or a provisional license would be barred from using cell phones and other wireless devices except in emergencies.

A license now requires a minimum of 60 hours of driving practice, compared with 40 hours before, and 10 of these practice hours must be at night.

"All too often, it's the combination of inexperience, inattention, immaturity and a false sense of invincibility that causes these serious bodily injury crashes that we all too frequently hear about," said Del. William A. Bronrott (D-Montgomery), a chief sponsor of three of the new driving laws. "What we're trying to do is give our kids more behind-the-wheel experience with fewer potentially deadly distractions."

In Maryland, the laws restricting teenage passengers and cell-phone use will be enforced as secondary offenses, meaning drivers must be pulled over for another infraction -- speeding, running a red light -- before they can be given a citation, Sgt. Rob Moroney of the Maryland State Police said. Violating the laws would result in a $60 fine and one point on the driver's license. If the violation occurred in the course of an accident, the fine is the same but three points would be applied.

"We know that text messaging and cell phones are very popular among youngsters. We hope they will use good judgment and not violate the law," Moroney said.

"Our point is deterrence and safe driving," Bronrott said. "Not to institute a new set of highly punitive laws."

But some parents and teenagers worried that the restrictions might have unintended consequences. Melissa's mother, Robin Justice of Prince Frederick, said it might be less safe to have Melissa driving alone.

"I don't think that it's good to have big groups of teenagers, but sometimes it's a little safer to have a pair," she said.

A survey last month of 100 students at Montgomery Blair High School in Silver Spring found that 70 percent of students believed the laws are too strict, according to an article from the student newspaper, Silver Chips. But of that 70 percent, 58 percent said that if none of the laws applied to them or their friends, they would be in favor of applying them to younger students, the article said.

Kernan said that many of his son's classmates at Gonzaga College High School in the District carpool to school and that the rules might prevent the younger drivers from such cooperation.

"But how can you disagree" with the rules? Kernan asked. "One death is too many."