Bill Blair, the Canadian government's point man on legalizing marijuana, speaks during a news conference Thursday in Ottawa. (Chris Wattie/Reuters)

OTTAWA — The Canadian government has introduced sweeping legislation designed to permit the recreational use of marijuana throughout the country by July 2018, fulfilling an election promise by Prime Minister Justin Trudeau.

The bill, inspired in part by the experiences of cannabis regimes in Colorado and Washington state, goes well beyond the U.S. situation, where marijuana remains prohibited at the federal level. In Canada, the federal government will change criminal law nationally and will license growers and set product standards while leaving it up to the provinces to handle distribution and manage retail sale.

Canada will become the first large industrialized nation with a broad system permitting recreational as well as medical use of marijuana. At present, only Uruguay has a national legal regime permitting widespread use of cannabis.

“The law as it stands today has been an abject failure,” said Public Safety Minister Ralph Goodale, noting that Canadian teens are among the world’s biggest users of cannabis, which they now buy from illicit sources.

Goodale was speaking at a news conference attended by four Liberal Party cabinet ministers, though Trudeau himself stayed away.

Under the proposed new system, individuals will be able to possess up to 30 grams of dried or fresh cannabis for personal use — about one ounce — and can grow up to four plants at home, provided they are not more than one meter high.

The minimum age for recreational use of marijuana has been set at 18, but provinces can decide to set a higher minimum age, as some do in the case of alcohol. And the federal government plans to impose penalties of up to 14 years in prison for selling or giving away marijuana to minors.

The government also proposed new legislation governing impaired driving that would make it illegal to drive within two hours if an illegal level of drugs is found in the blood. Police will be given authority to administer a saliva test for cannabis if a driver shows signs of use, including the smell of cannabis or reddened eyes.

Canada has permitted medical use of cannabis since 2001 and has a thriving industry of licensed marijuana suppliers who have been eagerly awaiting the opening of the recreational market.

Despite introduction of the legislation, there remains a lot to be done before the legal regime comes into place. Goodale, the public safety minister, warned that existing laws banning cannabis will remain in force until the new legislation is passed. “This needs to be an orderly transition,” he said. “This will not be a free-for-all.”

The government also hasn’t said how it will tax the products, and it has delayed regulations on the sale of edible forms of cannabis until a later date.

The legislation would prohibit marketing aimed at young people and would ban the sale of cannabis products in vending machines and self-service displays, but detailed packaging rules will only be decided after several consultations with industry and the public.

The government says advertising will be subject to restrictions similar to those affecting tobacco, but it does appear as if branding will be allowed.

Tourists visiting the country will be allowed to smoke pot at their pleasure but rules banning the import and export of marijuana will remain in force. In other words, people crossing from Washington state, where recreational pot is legal, into British Columbia could still be arrested if marijuana is discovered in their possession.

The provinces also have to figure how they will regulate distribution. Cannabis dispensaries have already opened in many cities across Canada catering to the medical marijuana trade, but pharmacies are also interested in getting part of the business. And in some provinces, the governments are anxious to allow their retail alcohol monopolies to sell cannabis as well.

Bill Blair, a member of parliament and former Toronto police chief who has led the government’s marijuana legalization process, said that the government consulted extensively with officials in Colorado and Washington. “We’ve tried to learn from their experience,” he said, noting that Canada has looked upon this as public health issue rather than a commercial opportunity and an effort to maximize tax revenue.

Although public opinion is generally supportive of cannabis legalization in Canada, some in the medical profession have expressed concern about the dangers posed by setting too low a minimum legal age. The Canadian Psychiatric Association has sought to ban sales to anybody under the age of 21 and limit the potency of products sold to people between 21 and 25.

“There is a strong evidence base showing that early and regular cannabis use can affect cognition, such as memory, attention, intelligence and the ability to process thoughts and experiences,” said Renuka Prasad, president of the association, who also noted that cannabis use can increase the risk of mental-health issues like depression and psychotic disorders in vulnerable young people.