Ontario's Liberal government has introduced legislation which will make it illegal for drivers under 21 to have any alcohol in their system when they're behind the wheel.

The change will also apply to every new driver during their first year on the road, no matter what the driver's age.

Another section of the bill will limit the number of teens allowed to be in a vehicle at one time.

The new rules are intended make the roads safer and come in response to two deadly crashes involving young drivers in the past couple of years.

In January 2007, five teens died when their SUV was involved in a collision near Meaford.

The crash on the south shore of Georgian Bay killed Michael Fleming, Drew Perry and Morgan Fitzgerald, all 16, and Andrew McKean and Michael O'Hara, both 17.

O'Hara was driving an SUV eastbound on Highway 26 near Meaford, 180 kilometres northwest of Toronto, on a Friday afternoon when the vehicle veered into oncoming traffic in the westbound lane and was broadsided by a cargo van.

Ontario Provincial Police said the three teens in the back were not wearing seatbelts and two of them were thrown from the vehicle.

Alcohol was not a factor in the crash, but speed and road conditions likely were, police said.

In the summer of 2008, three teens died when their car plunged into the Joseph River after they'd been drinking at a Muskoka resort.

The victims were Tyler Mulcahy and Cory Mintz, both 20, and 19-year-old Kourosh Totonchian.

A fourth person in the car, 19-year-old Nastasia Elzinga, also of Toronto, suffered minor injuries.

The new legislation will put a strict ban on drinking for any driver 21 and under.

If they're pulled over they will have to register a zero blood alcohol level on a breathalyzer.

As well, young drivers can only have one passenger 19 or under in their car when they're driving.

Safety experts like Brian Patterson, the head of the Ontario Safety League, support the new rules. He says it's not just about alcohol but also avoiding distractions for inexperienced drivers.

And Don Forgeron, the Ontario vice-president of the Insurance Bureau of Canada says saving lives is more important than inconvenience.

Forgeron says while 16- to 24-year-olds make up nine per cent of the population, they account for 25 per cent of the fatalities and serious injuries on the roads.

But the proposed legislation is not supported by many teens.

Already several online Facebook groups have sprung up protesting the proposed law. Teens are posting comments suggesting the law will discourage carpooling and having designated drivers.

"How does it make sense to try and teach us about saving gas by carpooling and buying hybrids and things such as that when it is illegal for teenagers to carpool if this passes?" one person wrote.

Another wrote that the law would "encourage drunk driving!"

"We would need more cars which means more designated drivers. My friends already don't want this job!"

Ontario Premier Dalton McGuinty called the changes "modest restrictions."

"Perhaps the most precious thing we have in society is our children, and that includes our older children," McGuinty said at Queen's Park.

"We owe it to our kids to take the kinds of measures that ensure that they will grow up safe and sound and secure, and if that means a modest restriction on their freedoms until they reach the age of 22, then as a dad, I'm more than prepared to do that."

Progressive Conservative Leader John Tory said he likes the idea of new rules for younger drivers, but worries the restrictions on teenage passengers could be unworkable, especially in rural Ontario.

"We want to protect public safety and have stricter conditions under which young people can drive cars, but we have to be careful of the practicalities of living," Tory said.

"In rural Ontario sometimes if you're going to a hockey game, a movie or just going to school … we have to be careful that we don't do things that are impractical."

With files from the Canadian Press